In a tweet, Trump wrote, "At least 24 players kneeling this weekend at NFL stadiums that are now having a very hard time filling up. The American public is fed up with the disrespect the NFL is paying to our Country, our Flag and our National Anthem. Weak and out of control!"
Trump has taken issue with anthem protests throughout the season dating back to September, when he told a rally in Alabama: "Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'Get that son of a b---- off the field right now. Out. He's fired! He's fired!'"
While NFL Commissioner Roger Goodell said earlier this season that he wants players to stand for the anthem, the league hasn't enacted a rule forcing them to.
Last week, the Washington Post (h/t ESPN.com) reported that some NFL owners think the league will change its anthem policy next season to keep players in the locker room during its playing.
Trump was also critical of that idea, tweeting, "The NFL is now thinking about a new idea - keeping teams in the Locker Room during the National Anthem next season. That's almost as bad as kneeling! When will the highly paid Commissioner finally get tough and smart? This issue is killing your league!"
Demonstrations during the anthem began last season when then-San Francisco 49ers quarterback Colin Kaepernick decided to do so in order to protest social injustice.