The official publication followed approval on Friday from the Constitutional Council that declared the plan to gradually raise the retirement age from 62 to 64 years essentially in conformity with the constitution. The law is to take effect in September.
A referendum, which opponents of the reform had hoped for, was declared inadmissible by the constitutional authorities.
That news was greeted by protests in Paris, Nice, Nantes, Rennes and other cities. In Paris alone, 112 demonstrators were arrested on Friday evening and 30 rubbish bins were set alight, the television station "BFMTV" reported, citing the police.
Photos showed burning rubbish bins in front of the Paris city hall. In several other cities such as Strasbourg, Lyon and Nantes there were also protests. In Rennes the door of a police station was set on fire. There had already been rallies and roadblocks earlier in the day.
Demonstrations are also expected on Saturday, while the trade unions called for new protest marches on May 1.
"The struggle continues and we must join forces," said left-wing politician Jean-Luc Mélenchon.
The Socialists announced a motion to repeal the law.
