Raphinha has apologised for winding up Atlético Madrid supporters after Barcelona's Champions League exit at the Metropolitano on Tuesday.
Video footage showed the Brazil forward on the pitch at the end of the game, gesturing to the home fans that they are "going out" in the next round.
He had not actually featured in the match, missing out due to a hamstring injury, but had travelled to Madrid to be with his teammates.
"I want to apologise for my gesture," Raphinha said in a comment on a DAZN Instagram post that showed him rowing with the crowd.
"It does not reflect my values or character. It was an act in a moment of tension, in response to a fan who was disrespecting me."
Barça lost the tie 3-2 on aggregate despite winning 2-1 on Tuesday, with Atlético advancing to a semifinal against Premier League side Arsenal.
Raphinha was seen gesturing towards the Atlético fans after Barcelona's exit from the Champions League. Alvaro Medranda/Quality Sport Images/Getty Images Raphinha could also find himself in hot water with UEFA after accusing the match officials of "robbing" Barça over the two legs.
His comments will be analysed -- as is due process -- to see if they are in breach of Article 11 of UEFA's Disciplinary Regulations, which require "persons to respect the Laws of the Game, regulations, directives and decisions, and comply with the principles of ethical conduct, loyalty, integrity and sportsmanship."
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He could face a ban of up to three games, which would be carried out in next season's Champions League.
Raphinha has not featured for Barça since the March international break, when he re-injured his hamstring in Brazil's loss to France, but he hopes to be back by May, with the Clásico against Real Madrid on May 10 the target.