The protesters were demonstrating against a meeting of the far-right CasaPound movement in the city centre on Thursday night when violence broke out.
Protesters, many with their faces covered, threw bottles at the police, while officers fired tear gas and used water cannons.
Two students were arrested.
All photos by Piero Cruciatti for AFP.
In a separate development, the National Association of Italian Partisans (ANPI), an antifascist movement, accused fascist arsonists of setting fire to the social centre of a local far-left group in Brescia, northern Italy, on Thursday night.
"They forced entry through a window and used gasoline to set the social centre bookshop on fire," ANPI Brescia said on Facebook.
Incidents between anti-fascist and far-right activists have dramatically increased in recent weeks, particularly since a racially motivated attack on February 3rd by a far-right gunman in the central city of Macerata, which left six African migrants wounded.
On Tuesday, a local leader of the extreme-right group Forza Nuova was beaten up by men wearing masks in Palermo, Sicily. The same night, Forza Nuova activists stormed a local television station, La7 TV, and demanded the right to participate in a political broadcast.
Also on Tuesday, an activist from the far-left Potere al Popolo movement was stabbed while sticking up posters in the central city of Perugia, according to judicial sources. The following day in Perugia, a fight broke out between Potere al Popolo members and far-right activists that left at least two injured.
Last week in Bologna police fired water cannons on anti-fascist protesters who wanted to stop a planned appearance by Forza Nuova leader Roberto Fiore, leaving four police and six demonstrators injured.
The violence comes amid fears of a revival of far-right parties ahead of the March 4th election.
An average of the last major polls suggested former prime minister Silvio Berlusconi's right-wing coalition, which includes his Forza Italia party and two far-right groups, could finish on top but fail to achieve a parliamentary majority.