Unions called on the government not to adopt the "unjust reform", which raises the minimum retirement age from 60 to 62 and increases the number of years' contributions needed to receive a full pension.
MPs cannot "scorn or ignore" workers' demands, they way in a communiqué.
School students have joined the protests this week.
How the strike is progressing
- Lorry-drivers' unions are calling on them to join the strike and are organising drive-slows on major roads;
- Trains: six per cent of SNCF employees were on strike on Thursday – down from eight per cent on Wednesday and 17 per cent on Tuesday;
- One out of every two Transilien trains will be running;
- Two-thirds of TGV trains to and from Paris and a quarter of provincial trains will be in action, according to the rail company, the SNCF. But it recommends postponing journeys to the south;
- Paris and its region's public transport is still seeing reduced services, although the métro and bus services are nearly normal, according to the system's management;
- Primary schools: the Ministry of Education says 0.8 per cent of primary school teachers were on strike on Thursday;
- School strudents at 306 of France's 4,302 high schools protested Friday morning.