Protesters attacked shop windows and cash dispensers in the east of Paris on Thursday after President Francois Hollande announced he would not abandon an unpopular labor bill, a Paris police spokeswoman said.
"There are 300 people currently causing very important damage," the spokeswoman said, adding that a police operation was under way but no arrests had been made yet.
Several marches have been taking place in Paris over the past two weeks on the sidelines of the occupation by left-wing and anarchist youths of the city's "Place de la Republique," a vast square in the east of the French capital.
Earlier on Thursday, dozens were arrested after clashing with police at the margins of a rally protesting controversial labor reform plans.
The "Nuit Debout" or "Up all Night" movement began on March 31 when a group of activists decided not to go home after a march against a proposed labor reform.