Protesters clashes with riot police on Foch avenue next to the Place de l'Etoile, setting cars ablaze during a Yellow Vest protest on December 1, 2018 in Paris, France.

The French government will consider imposing a state of emergency to prevent a recurrence of France's worst riots in years, but while it is open to dialogue it will not change course, its spokesman said on Sunday.

Masked, black-clad groups ran amok across central Paris on Saturday, torching cars and buildings, looting shops, smashing windows and fighting police in the worst unrest the capital has seen since 1968, posing the most formidable challenge Emmanuel Macron has faced in his 18-month-old presidency.

Disturbances also rocked several cities and towns and across France - from Charleville Mezieres in the northeast to Nantes in the west and Marseille in the south.

"We have to think about the measures that can be taken so that these incidents don't happen again," government spokeswoman Benjamin Griveaux told Europe 1 radio.

The popular rebellion erupted out of nowhere on Nov. 17 and has spread quickly via social media, with protesters blocking roads across France and impeding access to shopping malls, factories and some fuel depots.

The protests began as a backlash against Macron's fuel tax hikes, but have mined a vein of deep dissatisfaction felt towards the 40-year-old's liberal economic reforms, which many voters feel favour the wealthy and big business.

Authorities were caught off guard by Saturday's escalation in violence overshadowing the spontaneous protest movement, dubbed the "yellow vests" because many participants are wearing the fluorescent safety jackets kept in all cars in France.