"We have to improve and complete this draft law. But what we cannot do is maintain the status quo," Valls said in an interview with the weekly newspaper Journal du Dimanche.
"(We) cannot stand still even for a second. This labour law means more transparency for businesses and more protection for employees," he said.
The prime minister will meet with business and union heads from Monday, while a number of organisations have called strikes for Wednesday and demonstrations later in the month to protest against the plans.
Valls faces strong opposition from the left wing of his own Socialist Party, while seven in 10 French are opposed to the changes, according to a poll. Another survey showed two-thirds of people believe there will be widespread protests if the law is pushed through.
The reforms are part of government efforts to combat record unemployment levels in a country where employers are loath to take on permanent workers, as letting them go can be near impossible.
But critics complain the measures would dismantle one of the key job guarantees for French employees.
Currently French companies have to justify in court plans to shed workers due to an economic downturn, a process they have complained makes it difficult and expensive to trim staff when the economy slows and ultimately makes them reluctant to hire.
Submission of the proposals to the cabinet has been postponed from March 9 to March 24 in order for a compromise to be reached, according to a government source.