West Ham have been charged by UEFA following the behaviour of their fans at their midweek Europa Conference League final victory over Fiorentina.
The Serie A side's captain Cristiano Biraghi sustained a cut head after being hit by one of several plastic cups hurled at him from the end containing Hammers supporters as he went to take a first-half corner.
West Ham have also been charged with an invasion of the field of play.
Fiorentina have landed two charges relating to the lighting of fireworks and throwing of objects.
UEFA's Control, Ethics and Disciplinary Body (CEDB) will decide on the matter in due course.