Naples Mayor Rosa Russo Iervolino publicly apologised after fans of Liverpool were assaulted ahead of an Europa League game their side were to play against Napoli.
Local media reported that an English fan was stabbed and hospitalised on Wednesday night, when two other hooligan attacks took place in the city. The stabbed fan was dismissed shortly after being admitted.
A group of visiting fans was assaulted while eating in a restaurant and two in a group of four were beaten as they headed for their hotel.
In the last incident, a police car intervened and arrested three Napoli hooligans who were carrying clubs.
"It is a bad page for Naples and I am sorry that, because of just 15 violent persons, the whole city will again end up in newspapers and newscasts," Iervolino said.
"I appeal to all Naples citizens: let's show our usual hospitality."
The sale of alcohol was banned on Thursday in several parts of Naples, while soft drinks have to be sold in plastic or paper containers.
About 1,000 Liverpool fans are expected in Naples, where the hosts lie two points behind the English side, who lead Group K on four points after two games.
There is a general feeling of unrest in Naples, not connected to football and tension has been high for days in the city as officials have trouble disposing garbage due to a lack of empty dumps in the Campania region.