The man arrested at Fulham's training ground on Monday on suspicion of actual bodily harm and criminal damage was the club's French striker Aboubakar Kamara, BBC Sport understands.
Neither the club nor the police have confirmed his identity, but Fulham said the person arrested was now "banned indefinitely from all club activities".
Kamara, 23, joined from Amiens in 2017.
A Fulham statement added: "The club is grateful for the swift attention and action by the Metropolitan Police."
It continued: "We will refrain from further comment but stress that we will fully cooperate with any new or continuing investigation or legal proceeding in the name of providing everyone a secure and safe working environment."
Metropolitan Police said a man in his 20s was arrested at a training ground in New Malden on Monday and taken into custody in a south London police station.
Earlier this season, boss Claudio Ranieri said he "wanted to kill" the forward after Kamara missed a penalty against Huddersfield having refused to give the ball to designated penalty-taker Mitrovic.
He has made 15 appearances in all competitions this season for Fulham, who are second from bottom in the Premier League.