Protesters in Naples opposed to stricter coronavirus measures clashed with police late into the night.
Some threw smoke bombs and firecrackers in the centre of the southern Italian city; police responded with tear gas.
The mainly young crowd defied a night-time curfew imposed late on Friday in the Campania region after cases rose.
Regional President Vincenzo de Luca has called for a national lockdown to avoid a repeat of the casualties seen in the first wave earlier this year.
Hundreds broke through a police cordon near the regional headquarters building late on Friday, Italy’s Ansa news agency reports.
Along with smoke bombs, bottles were thrown at the 100-strong line of police in riot gear.
Demonstrators also gathered in front of a university building in response to calls on social media, one carrying a banner with the words “you close us, you pay us”.
Naples police commissioner Alessandro Giuliano condemned “criminal behaviour”.
“No conditions of discomfort, however humanly understandable, can in any way justify violence,” he said.
Italy, badly hit during the first wave of the virus in March and April, has seen a spike in new daily infections – 19,143 were registered on Friday. Ninety-one deaths were recorded, though that is much lower than the peak of fatalities in the first wave.
Regional leaders have the power to impose their own measures, but Campania’s president said regional lockdowns would not be enough.
“We need to make one last effort to get things under control. We need to shut everything down for a month, for 40 days,” he said in a statement posted on the regional government’s website.
Prime Minister Giuseppe Conte has said he does not want to repeat the national lockdown imposed during the first wave, as Italy continues to grapple with the severe economic consequences.
Campania is the second worst-hit region in Italy in terms of new cases, behind Lombardy, which was the epicentre when the pandemic first arrived in Italy.
More than 37,000 people have died with coronavirus in Italy, according to data from Johns Hopkins University, and over 484,000 have been infected.