WASHINGTON — President Trump began his first Thanksgiving vacation in office with an early-morning Twitter rage in which he again vented about some of his favorite targets: sports figures he thinks have defied him.

The president called LaVar Ball, the father of one of three U.C.L.A. players arrested in China for shoplifting, a “poor man’s version of Don King,” the black sports promoter. He also called Mr. Ball an “ungrateful fool!” and insisted that “IT WAS ME” who deserved more thanks for rescuing Mr. Ball’s son from the Chinese authorities.

Mr. Trump followed the angry rant toward Mr. Ball, who is African-American, with a return to his monthslong demand for football players to be more respectful while the national anthem is played — an issue that has strong support among some Americans. On the idea of asking players to stay in locker rooms during the anthem, Mr. Trump tweeted: “That’s almost as bad as kneeling!”

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Together, the posts were a reprise of Mr. Trump’s personal attacks against sports figures — many of them African-American — for what he judges to be poor behavior on their part and a failure to demonstrate enough deference to others.

White House officials deny that the president is focused on race when he comments about sports and athletes. But to historians and black activists, the tweets are clear evidence of an attempt by the president to send a message of solidarity to many supporters.

“President Trump appears to have a peculiar overfascination with African-American athletes and a negative fascination,” said Douglas A. Blackmon, the author of the Pulitzer Prize-winning book “Slavery By Another Name” and the host of “American Forum,” a weekly show produced by the University of Virginia’s Miller Center.

Twitter has long been the president’s preferred method for directing his outrage at individuals, and those of all races have been his targets, including Hillary Clinton; James B. Comey, the former F.B.I. director; and Khizr Khan, the Pakistani father of a fallen American soldier.

But Mary Frances Berry, who is African-American and who served as the chairwoman of the United States Commission on Civil Rights, said that Mr. Trump’s particular desire during his first year in office to lash out at African-American sports figures was hard to ignore.

“It just reinforces a theme that’s already on their mind,” Ms. Berry, now a professor of history at the University of Pennsylvania, said of the president’s tweets. “It’s tailor-made for him to spout off and reinforce his base.”

In addition to N.F.L. players and Mr. Ball, Mr. Trump has in the past tweeted angrily at other African-American athletes and broadcasters, including Stephen Curry, the star basketball player for the Golden State Warriors, and Jemele Hill, a sports journalist who is a host of ESPN’s flagship “SportsCenter.”

In the case of the N.F.L. players, Mr. Trump has played to the beliefs of his most conservative supporters by openly deriding Colin Kaepernick, the former San Francisco 49ers quarterback who last season kicked off the idea of sideline protests by kneeling.

Speaking to an adoring, and mostly white, crowd in Huntsville, Ala., in September, Mr. Trump referenced the actions of football players like Mr. Kaepernick who knelt during the national anthem and said he would love to see an N.F.L. owner say, “Get that son of a bitch off the field right now.”

On Wednesday, the president kicked off the first day of a five-day visit to his Mar-a-Lago club in Palm Beach, Fla., by focusing his ire on Mr. Ball, the outspoken father of the U.C.L.A. basketball player LiAngelo Ball, who, along with his teammates Cody Riley and Jalen Hill, was released from Chinese custody after Mr. Trump intervened.

Mr. Ball stoked the confrontation with the president this week, refusing on CNN to thank Mr. Trump for his assistance and saying that “I don’t have to say, to go around saying thank you to everybody.”

That interview appears to have prompted the angry response from Mr. Trump. He insisted that he was the one who rescued Mr. Ball’s son, and he chided Mr. Ball for refusing to give Mr. Trump the due he felt he deserved.

“LaVar, you could have spent the next 5 to 10 years during Thanksgiving with your son in China, but no NBA contract to support you,” Mr. Trump wrote, referring to another of Mr. Ball’s sons, who plays professional basketball. “But remember LaVar, shoplifting is NOT a little thing. It’s a really big deal, especially in China. Ungrateful fool!”

Mr. Trump has repeatedly denied that his criticism of kneeling is aimed at African-American players. “The issue of kneeling has nothing to do with race,” he tweeted in September. And White House officials have said the president’s tweets are about patriotism.

“This isn’t an us-versus them. This should be something that brings our country together,” Sarah Huckabee Sanders, the White House press secretary, told reporters in the days after Mr. Trump first raised the issue. “All Americans should be proud to stand up, salute that flag, salute that anthem and be part of that process.”

Polls suggest that many agree with Mr. Trump. One taken in September found that 49 percent of Americans agreed with the president that it was wrong for football players to kneel during the national anthem to express a political opinion, compared with 43 percent who said they were right to do so.

In some ways, Mr. Ball and Mr. Trump are made for each other: two publicity-seeking individuals who rarely shy away from a good verbal fight.

It was the success of Mr. Ball’s eldest son, Lonzo, as U.C.L.A.’s freshman point guard last season that gave Mr. Ball a platform to build a brand. Since then, he has often let loose a series of attention-grabbing statements, including once claiming that — in his prime — he could have beaten Michael Jordan one-on-one.

But some of Mr. Trump’s critics say the president’s attack on Mr. Ball was about more than just chest-thumping between the two men. They say it echoes what they view as an obsession by Mr. Trump on sports figures who are black.

Harry Edwards, a civil rights activist and professor emeritus at the University of California, Berkeley, said that Mr. Trump understood that attacking black athletes — who are among the most popular figures in African-American communities — sent a powerful signal to some of his most fervent voters.

“All of these attacks resonate with a base that have some severe perspectives on African-American equality and justice,” he said. “To attack African-American athletes is really a way of sending that message that these are others.”

Mr. Trump’s decision on Wednesday to revisit the issue of football players who kneel at games appeared to have been set off by a Washington Post article that said that the league was considering a policy change under which players would stay in the locker room during the playing of the anthem. A league official said Wednesday that the idea was not currently under consideration.

Mr. Trump has excoriated the N.F.L. for allowing players to kneel, which he sees as disrespecting the American flag. In his tweet on Wednesday, the president criticized Roger Goodell, the longtime leader of the football league, asking “when will the highly paid Commissioner finally get tough and smart? This issue is killing your league!”

Mr. Blackmon said Mr. Trump’s focus on the actions of the players suggested that he took a particular affront when his expectations of their behavior was not met.

“This consistent pattern — African-Americans who stand up in a sense to him, who do not seem to be sufficiently compliant — seem to draw particular ire,” Mr. Blackmon said.