President Trump said Thursday that NFL owners won't prohibit their players from kneeling during national anthem because they are "afraid of" them.

"I have so many friends that are owners, and they are in a box. I mean, I have spoken to a couple of them. They say, ‘We are in a situation where we have to do something,'" Trump said on Fox News Thursday. "I think they are afraid of their players, you want to know the truth. And I think it's disgraceful. They've got to be tough and they've got to be smart."

During a rally in Alabama on Friday, the president called on NFL team owners to fire any player who takes a knee during the national anthem and has since condemned NFL players on Twitter if they kneel.

Trump also has urged fans to boycott games, and said the league needs to implement a rule prohibiting players from kneeling when the "Star-Spangled Banner" plays.

The president has said the NFL's low ratings and attendance at games can be attributed to fans who oppose players kneeling during the national anthem, and said the league has "no choice" but to require players to stand.

"They have rules for everything," he said during the interview broadcast Thursday. "You can't dance in the end zone. You can't wear the pink socks relative to breast cancer, which one of the players — they have rules for everything. Why aren't they honoring this country by enforcing a rule that's been in existence for a long time? So the NFL and the players really have to do the honor of the country. It's for the honor of the country. They have to respect our country. They have to respect our flag and our anthem."