Clashes took place on the sidelines of a march in France's capital on Sunday, with demonstrators protesting the policies of recently reelected French President Emmanuel Macron.
Most of the protesters were peaceful, but violence broke out at two points along the route.
Police intervened when a group reported to be "Black Bloc" anarchists tried to erect a barricade near Paris's La Republique Square. Windows of local business were also reported to have been smashed.
There were some 250 large rallies in cities across the country, including Lille, Nantes, Toulouse and Marseille.
Macron faces strong resistance to his plans, seen by some opponents on the left as pro-business. Among his policies is an increase of the retirement age to 65.
The cost-of-living crisis was also a major theme of the protests — as it was in last month's election campaign.
The French president won a new five-year term after fending off a challenge from far-right populist rival Marine Le Pen in last Sunday's runoff vote.