There have been reports of sporadic violence, including clashes between youths and police in Toulouse, but an overall drop in violence that began on Tuesday night appears to be continuing.
The Paris area, where the riots began, is said to be calm.
Rights groups have angrily condemned comments by France's Interior Minister Nicolas Sarkozy who said non-French nationals convicted over the riots would be deported.
He told Parliament that 120 foreigners had been found guilty of involvement and would be deported without delay.
Less than 400 vehicles were burned across the country by 4am on Thursday, down from 558 at the same time on Wednesday, with arrests also down and no policemen injured.
Five out of 25 regional departments which have been given the power by the government to impose curfews have taken the step so far.
Curfews have notably been declared in 21 towns and cities on the French Riviera, including Nice, as well as Amiens north of Paris, the western towns of Rouen, Le Havre and Evreux, and the Loire Valley city of Orleans.
No curfews were planned for the Paris region.
The order bans unaccompanied children under 16 from leaving their homes between the hours of 10pm and 5am, and also widens police search-and-seizure powers, ban meetings likely to fuel disorder and conduct house searches.
According to a poll in Le Parisien newspaper, 73 percent of French people back the curfews.
Support for powers
Mr Sarkozy told MPs on Wednesday that non-French nationals had been convicted of taking part in the attacks.
"I have asked the prefects to deport them from our national territory without delay, including those who have a residency visa," he said.
Since it began, the unrest has left one civilian dead and dozens of police injured, and cast a cruel light on France's failure to integrate immigrants from its former African colonies.
The riots have been carried out by youths mainly from the Arab and black communities that dominate poor out-of-town neighbourhoods.
According to official figures, 1,800 people have been arrested, of whom 173 have been sentenced to prison with more facing court.
However, the recourse to the emergency law -- originally enacted 50 years ago to deal with the insurrection in Algeria, then a French colony -- has angered the opposition and Algerian immigrants.
The violence was sparked by the deaths of two teenagers of African origin in the Paris suburb of Clichy-sous-Bois who were electrocuted as they hid from police.