Jude Bellingham slapped Argentina substitute Valentin Barco on the back of the head following England’s 2-1 World Cup semi-final defeat.
Barco, who did not play in the game, came on to the pitch at full-time and was hugging team-mates near Bellingham when the England midfielder walked over and slapped him.
It sparked a small melee as players from both sides got involved before Bellingham walked away.
It is not known what prompted the reaction, but footage showed Barco running on the pitch after Enzo Fernandez’s 85th-minute equaliser and celebrating in front of the England players.
Former England goalkeeper Paul Robinson, commentating on the match for BBC Radio 5 Live, described Barco’s actions as “probably the worst example of sportsmanship we’ve seen at this World Cup”.
Bellingham could face action from Fifa’s disciplinary committee for violent conduct.
Being found guilty of such a charge would result in the 23-year-old being suspended for Saturday’s bronze medal match against France in Miami (kick-off 22:00 BST).
However, Fifa is more likely to consider the act as petulant rather than violent.
The laws of the game state there is no red-card offence if a player deliberately strikes an opponent on the head and the force used is negligible.