White House Chief of Staff John Kelly. Associated Press/Carolyn Kaster White House chief of staff John Kelly was displeased with President Donald Trump's antagonizing NFL players who kneel in protest of police violence and racism during the national anthem, two administration officials said in a CNN report on Monday.

Kelly was cognizant of racial issues and was concerned with the matter, one official said.

Despite his reservations with Trump's NFL war, Kelly, a highly decorated former Marine Corps officer and the former Homeland Security Secretary, publicly said he was "appalled" by the players who knelt during the national anthem.

"I believe every American, when the national anthem is played, should cover their hearts and think about all the men and women who have been maimed and killed," Kelly said to CNN on Monday. "Every American should stand up and think for three lousy minutes."

The chief of staff was also reportedly concerned with Trump's initial response during the white-nationalist protests in Charlottesville, Virginia, in August, according to CNN.

Trump rejected CNN's assertion that he and Kelly were at odds on his NFL tirades, calling it a "total lie," and insisting that Kelly "agrees [with] my stance on NFL players."

Trump found himself mired in controversy after suggesting NFL team owners should fire players who knelt during the national anthem, during a rally in Huntsville, Alabama, on Friday.

"For a week, they'll be the most popular person in this country," Trump griped about players kneeling during the national anthem. "Because that's a total disrespect of our heritage. That's a total disrespect for everything we stand for."

Trump carried on with the subject through the weekend and all day Monday, telling players who demonstrate to "find something else to do" and calling the NFL's games "boring."