PARIS — Hoping to tamp down the transport strikes that are choking France, Prime Minister Edouard Philippe promised in a much-anticipated speech on Wednesday that the government’s planned pension overhaul would not affect older workers and would have a limited effect on those now in midcareer.

But he again angered the unions on a crucial point — pushing the French to work longer — raising doubts about an early end to the strikes, which have also hit schools and government services, and setting up a possible prolonged battle between workers and the government of President Emmanuel Macron.

Mr. Philippe, the president’s stoic frontman for the pension plan, said that through incentives and penalties, the French would be encouraged to work until 64, past the legal retirement age, 62, one of the lowest in Europe. He also made concessions on the start date of the changes, which would go into effect in 2022, but only progressively, and at an even slower pace for those, like railway workers, who are currently in “special” retirement schemes.

But the new age target was too much for a critical moderate union, the French Democratic Confederation of Labor, or C.F.D.T., whose support the government needs and which had held back from the strikes.