Rome - About 150 anarchists from several countries have rioted in Venice, spray-painting windows, the walls of historic buildings and cash machines with slogans, Italian media reported on Sunday.
Nobody was injured during the riot, which occurred late on Saturday afternoon.
The famous Rialto Bridge was closed for a while, as tourists and Christmas shoppers fled in fear.
There were many French and German citizens among the rioters, Ansa news agency reported.
The rioters chanted against the city's conservative mayor, Luigi Brugnaro, the banks, telephone companies and capitalism in general.
Police were able to prevent the anarchists, mostly wearing motorbike helmets and masks, from forcing their way onto St Mark's Square.
It was not clear how many arrests there were.
The demonstration was apparently prompted by a reprimand for four of the anarchists given by the head of the Venice police department in September.