French Prime Minister Dominique de Villepin refused to withdraw the controversial First Employment Contract (CPE) job plan at talks with the five major French trade unions on Friday.
"Together we must succeed in finding constructive solutions to respond to the real anxieties of young people, notably on the CPE, " he said in a statement.
French Interior Minister Nicolas Sarkozy warned Friday that the demonstration was "taking on a new aspect" with the involvement of growing numbers of opportunist vandals.
Two weeks of protests against the CPE and four days national strikes have led to serious disturbances in the country's two- third universities and some 25 percent of the country's 4,370 high schools. Another day of national strikes has been planned by unions for Tuesday.
Across the country police have made 1,420 arrests since the start of the trouble.
Aimed at solving unemployment and removing employers' fears that they could be entangled in a costly long-term commitment if a worker proves unsuitable or if economic conditions deteriorate, the French parliament adopted the CPE two weeks ago, which encourages employers to hire young people under 26, with an open- ended two-year contract that could be terminated without explanation.
Opponents have said the law infringes workers' rights, making it harder for young people to get long-term employment.
Opinion polls show that some two-thirds of the population want the CPE either modified or dropped altogether.