The demonstration in Milan on Saturday remained peaceful, but there were brief clashes with police in both Rome and Turin.
In Milan, thousands of young people marched the streets as soldiers were deployed and luxury boutiques were boarded up, but by late afternoon, most shops had opened, Italian media reported.
Premier Giorgia Meloni announced a raft of measures, including sending an additional 500 soldiers to Milan and tougher penalties for minors, who made up a large part of the violent protesters last week. In Milan, police detained several minors as a preventive measure.
While protests in France have claimed most international attention, large demonstrations also rocked many European cities Saturday from Milan to Rome to Madrid, Lisbon and Tirana.
The protests encompass a broad range of issues from education and corruption to anti-war movements, pensions and housing.
In Milan, huge crowds of mostly young people gathered as night fell, chanting insults to Meloni and holding aloft banners such as "No to lies of the state".
The 500 soldiers deployed to Milan came in addition to hundreds already stationed there, supporting about 5,000 police and other security personnel. Authorities used drone surveillance, checks at railway stations, rapid-response units and online monitoring for potential calls to violence.
Many stores, particularly luxury boutiques within Milan's fashion district including Omega, Tiffany and Gucci, boarded up their front windows. The Apple store also shut down.
Rioters last weekend smashed their way into stores, targeting sneakers, athletic wear and sporting goods on streets that run off the city's central Duomo square.
Milan police say last week's violence and looting involved about 2,000 very young protesters, many of them "naturalized, second-generation Italians," alongside foreign nationals. Over two days, police arrested 45 people, including 34 minors.
A group of about 30 far-right activists, described as hooligans linked to Inter Milan soccer club, made a brief appearance chanting anti-immigrant and anti-Muslim slogans but were isolated by police.
Security was also heightened in Rome, where authorities locked down luxury shopping streets and stepped up controls around the Circus Maximus and Piazza del Popolo.
A small number of protesters tried to force their way into the Colosseum, but were ushered out by guards. Elsewhere, several hundred students demonstrated peacefully to stress they were not rioters.
In Albania's capital Tirana, riot police used water cannons on large groups of protesters, some of whom set government buildings on fire and threw projectiles at police. Authorities said 2,500 officers patrolled the streets on Saturday.
Thousands of retirees and others marched peacefully in Spain's capital Saturday to demand public pensions aren't meddled with.
The protests came ahead of November's election as Prime Minister Pedro Sánchez's Socialist Party criticised the conservative opposition Popular Party for making overtures about privatising public pensions.
Protesters in Lisbon demanding affordable housing marched across the city on Saturday.
