The incident near Sorbonne University highlighted the risks of protests getting out of hand as students sought to keep pressure on the government. Ruling party lawmakers looking for a way out of the crisis wrapped up talks with union and student leaders Friday.
The law, which would make it easier for companies to hire and fire people under age 26, has sparked weeks of strikes and massive protests. While most demonstrations have been peaceful, some have seen violence.
This week, students have switched to more unpredictable methods of protest, with impromptu blockades of train stations and roads.
On Paris' Left Bank, protesters disrupted traffic by picnicking on a busy boulevard. They were heading away when a motorist tried to drive through the crowd.
The famous Sorbonne University has been shuttered for weeks with bloody clashes between students and police there on several occasions last month, CBS News reports.
Several dozen youths turned the car over and unsuccessfully tried to drag the driver out before police and onlookers intervened. Police in riot gear and helmets worked to disperse the crowd. Firefighters said seven people suffered slight injuries, and police detained the driver.
A day earlier, students blocked international trains in Paris and a convoy carrying parts for the new Airbus A380 jet to a factory in southwest France.
Trying to end the standoff, President Jacques Chirac has offered to soften the law. But unions and students want it repealed by April 15 and have threatened more protests.
The government was expected to decide on action in the coming days. Lawmakers close to Interior Minister Nicolas Sarkozy said one possible way out might be drawing up measures with labor leaders to replace the law.
"We are moving toward the opening of negotiations," said lawmaker Dominique Paille. Another lawmaker, Yves Jego, said the idea had the backing of many in parliament. But it was unclear whether it would satisfy unions, or whether it had Chirac's backing.
Many universities have been barricaded for weeks, and some high schools have been disrupted. Friday marks the start of spring break for many students. While the pressure has so far been on the conservative government, the onus is shifting to students to keep momentum going during the holidays.
Adrien Taieb, a 21-year-old computer science student at the University of Paris 7 — closed for five weeks — said protesters would not back down.
"We will still be here, because since we're students, we don't have the money to go anywhere," he said. "This is going to last because we're not ready to give in."
The government's new law is designed to inject flexibility into France's rigid labor rules, and to chip away at the 23 percent rate of youth unemployment that climbs above 50 percent in the depressed, heavily immigrant suburbs hit by riots last fall.
It originally provided for a two-year trial period during which employers could fire youths without cause, although Chirac offered to reduce that to one year.