Protests that began in northern France spread to the capital's outskirts on Friday, where police said they arrested 10 people after high-school children rioted, damaging cars by turning them on their side or smashing windows.
Another 18 were arrested in northern France, where protesters attacked buses, torched bins and allegedly insulted a police officer.
Around 20 schools were affected in the Picardy region, north of Paris, including in Amiens, where pupils set fire to bins and threw stones, eggs and tomatoes.
Staff at the Jean-Moulin high school in Le Chesnay, near the Chateau of Versailles, where revolutionaries marched against France's absolute monarchy in 1789, said children were refusing to return to class.
"We've made a blockade because President Sarkozy wants to take a month's holiday away from us and that's why we've revolted," a 15-year-old schoolgirl told AFP, asking not to be named.
She admitted that it was "disgusting that people's cars got smashed up."
"This is gratuitous, they don't know what they're doing," said an angry woman in her 50s upon seeing her damaged car, also requesting anonymity.
Several hundred schoolchildren protested in northern French cities on Friday morning, local education officials said. Around 500 high-school students protested in Douai and another 500 in Lens, damaging property, police said.
"We can't make head or tail of it. We don't know how the rumour started," said a local education official, who asked not to be named, slamming what he called "orchestrated disinformation."
The official said the rumour was "spreading like wildfire" via SMS text message and Facebook.
The protests apparently kicked off in the northern town of Lens, where around 200 people demonstrated on Thursday, after which police were told to deal firmly with the protests which were described as "unstructured".
Several hundred pupils demonstrated in other towns on Friday, including the Channel port of Dunkirk, and tried to block access to schools.
The head of the National High-school Students Union (UNL), Victor Colombani, told AFP that the SMS circulating saying holidays would be slashed by a month was "quite curious" but "it doesn't come from us."
The UNL however "warned the government not to touch summer holidays at all" and said in a statement it wanted to protest austerity measures that amounted to "a catastrophic new term" in 2011.
The union criticised school conditions, with thousands of teaching jobs slashed, called for the reform of teacher training and for students to join a day of protest on October 11.
A steering committee on school holidays has in fact suggested cutting summer holidays by two weeks and increasing the autumn half-term holiday by a week, although no decision has yet been taken.
Education Minister Luc Chatel said in July that he wanted to hold talks with teachers' unions ahead of announcing measures later this year that could come into effect as early as the end of summer holidays in 2013.