In Lyon, police fired tear gas to disperse stone-throwing youths at the city's historic Place Bellecour.
Authorities imposed a weekend curfew on 10 towns in south-eastern France and in Lyon, barring minors from being outside without adult supervision between 10 pm and 6 am.
In Paris, 3,000 police fanned out to counter feared attacks on high-profile targets such as the Eiffel Tower.
Authorities banned public gatherings considered risky until Sunday morning, after "violent actions" were posted on numerous Internet blogs and sent in mobile phone text messages.
The anti-racism group known as MRAP - the Movement Against Racism and For Friendship - also demonstrated in Paris, at Saint-Michel, a Left Bank student haunt, to protest against the state of emergency.
MRAP claimed the demonstration was not illegal, as the ban on meetings was only for those deemed risky.
The unrest has forced France to confront the touchy issue of the poor suburbs ringing big cities populated by immigrants and their French children.
They face soaring unemployment, poverty and discrimination on a daily basis.
Authorities have acknowledged the roots of the problem are deep-seated, perhaps linked to the French approach to immigration which works to fit immigrants into a single mould.
The unrest was triggered by the accidental deaths of two teenagers in Clichy-sous-Bois.
The violence peaked last weekend, when vandals burned 1,400 vehicles in one night of nationwide mayhem.