Donald Trump has urged NFL fans to boycott games as he renewed his attack on players kneeling during the national anthem ahead of games.
The president has previously called on American football players who have been taking a stand by kneeling or raising their fist during the Star-Spangled Banner since the start of last season, to be fired.
High-profile figures such as Colin Kaepernick, Michael Bennett and Marshawn Lynch have been taking the stance in protest of perceived racial injustice and police brutality.
In his latest tweets, Mr Trump encouraged football fans to "refuse to go to games until players stop disrespecting our Flag & Country".
There has been criticism of Trump's call for the players to be fired including by the NFL Players' Association and team bosses.
At Sunday's NFL game in London at Wembley at least seven Baltimore Ravens players and more than a dozen Jacksonville Jaguars players took a knee during the anthem while the rest of the players stood locked arm-in-arm in an apparent response to Mr Trump's comments.
Baltimore Ravens owner Steve Bisciotti says he "100 percent" supports his players' decision to kneel, while Jaguars owner Shad Khan stood arm-in-arm with his players during the anthem.
Singing legend Stevie Wonder also showed his solidarity with #TakeAKnee when he knelt on stage during a performance at the 2017 Global Citizens Festival in Central Park, New York.
Mr Trump also criticised the commissioner of the National Football League.
He tweeted on Saturday: "Roger Goodell of NFL just put out a statement trying to justify the total disrespect certain players show to our country.Tell them to stand!"
In response, Mr Goodell said the president's "divisive comments" demonstrate an "unfortunate lack of respect".
American sport stars have also condemned Donald Trump after he rescinded an invite for NBA champion Stephen Curry to visit the White House after Curry said he would vote not to attend an event there.
The president's two-day rant on Twitter, which began when he withdrew Curry's invitation to the White House for "hesitating", drew condemnation from stars including basketball player LeBron James, who called the president a "bum".
On Friday Mr Trump announced he was withdrawing Curry's invitation for the commemorative visit traditionally made by championship teams.
He wrote: "Going to the White House is considered a great honor for a championship team. Stephen Curry is hesitating, therefore invitation is withdrawn!"
Speaking in response to James' tweet, Curry said: "That's a pretty strong statement.
"I think it's bold, it's courageous for any guy to speak up, let alone a guy that has as much to lose as LeBron does and other notable figures in the league. We all have to kind of stand as one the best we can."