France's interior minister said security forces would remain in place "as long as necessary" after a second night of violence in the Paris suburbs sparked when police stopped a woman for wearing a veil.
Manuel Valls said he would keep in place "a significant police presence until a lasting calm is restored" in and around the satellite town of Trappes, southwest of Paris.
Police made four arrests in the region early on Sunday as they came under a hail of projectiles and rioters burned about 20 vehicles in Trappes and surrounding areas.
Things were calmer than on the previous night, when 250 youths gathered in Trappes and hurled stones at police, who responded with tear gas.
A 14-year-old boy suffered a serious eye injury and several police officers were also hurt.
The unrest was sparked last Thursday when an officer stopped a woman wearing a veil. During the inspection, her husband attacked and apparently tried to strangle the officer. But Muslim groups accused the police of provocation.
The interior minister defended the ban on wearing full-face veils in public places and said the police officers acted with respect towards the woman when conducting their check.
"Police did their job perfectly," Valls said. "The law banning full-face veils is a law in the interests of women and against those values having nothing to do with our traditions and values. It must be enforced everywhere."
The law was brought in by conservative former president Nicolas Sarkozy and targets burqa and niqab garments that conceal the face rather than the headscarf that is more common among French Muslim women.
Since April 2011, France has had a ban against the full facial veils, outraging many in its Muslim community.
France has Europe's largest Muslim population, estimated at about five million. Yet according to interior ministry figures only between 400 and 2,000 women wear the veil and only a handful have been fined €150 (HK$1,500) for wearing it.
Critics say the law is patchily enforced as police seek to avoid confrontations in poor neighbourhoods with large Muslim populations.
A similar outbreak of unrest occurred last month when authorities stopped a 25-year-old woman in Argenteuil, a suburb northwest of Paris, who was wearing a full-face veil, or niqab.
An angry crowd gathered and police fired tear gas and rubber bullets to disperse them.
Trappes, a poor suburban town outside Paris with a large immigrant population, is well-known for producing some of France's biggest comedy stars, including the comedian Jamel Debbouze and the actor Omar Sy, as well as soccer player Nicolas Anelka.
The right was quick to accuse the Socialist government of not being tough enough on law and order, while the left accused right-wing politicians of trying to exploit events to stigmatise people in the poor suburbs.
In 2005, France declared a state of emergency after the worst urban rioting for 40 years was sparked by the death of two boys who had been running from police in a suburb northeast of Paris. Since then, tensions between police and young residents have remained high on suburban estates.
Agence France-Press, Reuters, The Guardian