Former San Francisco 49ers quarterback Colin Kaepernick started the movement last season of taking a knee during the anthem.
Since leaving the 49ers, Kaepernick has not been offered another NFL contract.
Trump has tweeted dozens of times against the mostly African-American players engaging in the protest.
“He has been targeting athletes largely from regions where he has no hope of winning the electoral vote," said Daniel Durbin, director of the USC Annenberg Institute of Sports, Media & Society.
“It makes it easy to use them as whipping posts -- in order to try and foment interest and support from people who are not from those regions of the country," he said.
Over the weekend Trump called out three UCLA basketball players, saying he should have left them in jail in China after they were caught shoplifting in Hangzhou. Trump helped arrange their release, but said in a Sunday tweet that the father of player LiAngelo Ball was “unaccepting” of his efforts.
White House Press Secretary Sarah Huckabee Sanders said on Monday that Trump was just being rhetorical when he said he should have left the players in a Chinese jail.
Durbin said Trump is adept at using his Twitter account “to disrupt conversation and direct it in ways that benefit him.” Since he’s the president of the United States, Durbin says, the press is forced to cover his constant tweets.
Earlier this year, Trump called on the NFL to fire all players who kneel during the anthem.
To date, the NFL has said it will not force players to stand for the anthem.
Neither the NFL nor the players union responded to requests for comment on Trump’s latest tweet against Lynch.