Czech police said Fiorentina fans attacked West Hams fans in Prague on June 7, ahead of the Europa Conference League final. They said 16 arrests were made.
Three people were injured and one policeman was attacked, police said.
Video posted by Jan Kokes shows clashes between the groups of fans, with some West Ham fans seen throwing objects while flash bangs and smoke grenades go off.
Police are later seen, as broken glass, chairs, and other objects are strewn across the street.
West Ham won their first major trophy in 43 years, defeating Fiorentina 2-1 on the night. Credit: Jan Kokes via Storyful