Fighting broke out in the centre of Naples between Napoli and Eintracht Frankfurt fans ahead of the teams Champions League match on Wednesday.
Motorcycles and cars, including a police vehicle, were set on fire while some shops were damaged.
Angry Napoli fans attacked buses as police tried to escort Eintracht supporters through the narrow streets in the centre of Naples.
Police in riot gear tried to calm the situation and get fans to return to their hotels.
Due to previous unrest between supporters during the first leg in Germany, Naples authorities issued a ban on any fans residing in Frankfurt from buying tickets. The club condemned the decision by forgoing its allocation of tickets for the round of 16 matches. Despite this, 600 fans from Germany arrived in the Italian city, putting local authorities on high alert.
Napoli went on to win the match 3-0 but local police made several arrests in the build-up amid altercations between fans.
The mayor of Naples, Gaetano Manfredi, said the incident created “an unacceptable climate of guerrilla warfare” in the city adding that the damage wreaked by the German fans is “unacceptable”.