French President Francois Hollande has called for the Uber taxi service to be shut down and its vehicles seized.
But Uber is refusing to stop the service until a ruling by the country's top court.
The stand-off, and a violence-marred taxi strike in Paris, reflects wider tensions in France over how to regulate fast-moving technology and stay globally competitive while ensuring labour protections.
France's top security official, Interior Minister Bernard Cazeneuve, said today that Uber is facing multiple investigations. He spoke to RTL radio a day after striking taxi drivers attacked Uber livery cars and set fire to tyres on a major artery around Paris.
Some taxi drivers continued the protest today, but the strike did not appear to seriously disrupt morning travel around Paris, and no violence was immediately reported.
Uber's cheapest service, called UberPop in France, has been banned, but Uber officials insist they will continue their activities until France's highest court rules on the service.
Mr Cazeneuve called that "cynical and arrogant".
Mr Hollande said today: "The UberPop group must be dissolved and declared illegal, and the vehicles must be seized." But he said the executive branch cannot do that without further action through the courts.
The president, speaking at an EU summit in Brussels, accused Uber of not respecting "social and fiscal rules".
Uber argues that the French taxi system is outdated and needs reform to keep up with apps and geolocalisation, and that traditional taxis are just trying to quash competition.
The company faces similar legal challenges and criticism from taxi drivers' associations around the world.
Furious taxi drivers in France say the low-cost UberPop service is ruining their livelihood. Uber drivers have been repeatedly ambushed, sometimes with customers inside.
Tensions have also risen in London over taxi-booking services such as Uber.
Black cab drivers have criticised Mayor Boris Johnson for failing to regulate the taxi trade effectively.
Cabbies also claim Uber does not pay UK taxes and is not subject to the same restrictions as traditional black-cab operators.