West Ham and Fiorentina have been charged by UEFA for incidents surrounding the Europa Conference League final in Prague earlier this week.
The Hammers have been charged with invasion of the field of play and throwing of objects, while the Serie A side are charged with throwing of objects and lighting of fireworks.
Disciplinary proceedings have been instigated in accordance with Article 55 of the UEFA Disciplinary Regulations.
The game was halted after a cup thrown left Fiorentina captain Cristiano Biragi bleeding from the head.
Plastic pint glasses were hurled from the West Ham end throughout the first half at the Eden Arena in Prague.
Referee Carlos del Cerro Grande eventually halted play after Fiorentina captain Biraghi was hit by another object as he went to take a corner just after the half-hour mark
Biraghi suffered a cut to the back of his head and required treatment and a bandage.
A message over the PA system urged supporters to stop throwing things on to the pitch and to respect the players, before play eventually resumed with the score still 0-0, before West Ham went on to win 2-1 thanks to Jarrod Bowen's last-minute goal.
West Ham released a statement condemning fans who threw objects onto the pitch during Wednesday's Europa Conference League final in Prague.
"West Ham United unreservedly condemn the behaviour of a small number of individuals who threw objects onto the pitch during tonight's UEFA Europa Conference League final," the statement read.
"These actions have no place in football, and do not in any way represent the values of our football club and the overwhelming majority of our supporters, who have behaved impeccably in Prague this week and throughout our last two seasons in European competition.
"We will work with the police and other stakeholders to review the incidents and act against anyone found guilty of an offence. In line with our zero-tolerance approach, anyone identified will have their details passed to the police and will be given an indefinite ban and therefore be unable to enter London Stadium and travel with the club.
"There is no place for this kind of behaviour at West Ham United."
