Twelve arrests were made after overnight clashes between French police and about 100 people in Paris.
The police said the clashes took place from Friday night to early Saturday around the Place de la Republique on the sidelines of the Night Rising protest movement.
A police car was set on fire and projectiles were thrown at police. The police used tear gas to disperse the crowd around 2am. No injuries were reported.
The Night Rising movement started on March 31 when some protesters denouncing the government's labour law changes decided to camp overnight in Place de la Republique.
The square in eastern Paris became a symbolic gathering place after last year's deadly attacks upon Parisians.
Police on Saturday issued a ban on consuming alcohol by the square at night "for security reasons". It said incidents "have been fuelled by the consumption of alcohol".
The ban, valid until Monday, also prohibits bringing alcohol to the square and selling alcoholic beverages to take away.
Consumption of alcohol is generally allowed on the streets in France but local authorities can apply restrictions in certain areas.