With the cost of living rising, strikers are calling for higher wages, better methods for protecting employment and higher taxes for high earners.
"The crisis is not the fault of the workers," one banner read at the biggest march in Paris, where 85,000 people marched through the city, according to police.
Public transport and schools, hospitals and the postal service have been affected by the strikes, which are supported by around 75 per cent of the population, according to opinion polls.
About one third of schoolteachers took part in the strike on Thursday, along with a quarter of employees at France Telecom and one in five postal workers, officials said.
Private sector workers also participated in the protests, including employees of Air France and oil company Total.
In Clairoix, a town in France's north, around 10,000 people protested over the closure of a Continental tyre plant, which has meant a loss of 1,120 jobs.
Estelle Youssouffa, Al Jazeera's correspondent in Paris, said the government has little resources to help the workers.
"President Sarkozy cannot do much really, he has already said he has very little room to manouevre, the coffers of the French state are empty," she said.
"Sarkozy has already said that despite the large turnout nothing more can be done.
"But the people are determined, and desperate. They don't believe the economic package will have any benefit to them".
'Sense of injustice'
Agnes Poirier, a French political commentator, told Al Jazeera people are "very disillusioned" with Sarkozy's government.
|Sarkozy faces pressure to alter his domestic agenda in the face of demonstrations [AFP]
"Every single corporation in France has a motive, a reason to demonstrate today. The French in their majority are protesting against a string of what they considered as ill-advised and rushed reforms that president Sarkozy wants to implement," she said.
She added that despite the majority of the population supporting the demonstrations, Sarkozy is unlikely to back down.
"The government is very cautious because it knows that there is popular support for these demonstrations, and yet Nicolas Sarkozy said yesterday that he wouldn't back off and he would actually press on with his reforms," she said.
"A very strong sense of injustice is building up," Jean-Claude Mailly, head of the Force Ouvriere Union, told the Reuters news agency.
"I think the government will find it hard to ignore us."
The government has introduced a $34bn stimulus plan aimed at business investment, and after the January 29 strike Nicolas Sarkozy, the French president, offered more money to help vulnerable households weather the crisis.
Ministers say there will be no more concessions, explaining that the previous measures have not yet taken effect and warning that the heavily-indebted nation cannot afford more handouts.
Underlining the tensions, workers at a tyre factory in northern France recently pelted managers with eggs after they were told it was closing and, last week, staff at a Sony plant locked up their bosses for a night to demand better redundancy cover.
With its large public sector and welfare system, France is better placed than many to ride out the economic storm, but is still being strongly affected, with some analysts predicting the economy will contract by two per cent this year and unemployment jump to almost 10 per cent.