French President Emmanuel Macron on Wednesday said a deeply unpopular new law that raises the retirement age was necessary and would enter into force by the end of the year.

"Do you think I enjoy doing this reform? No," Macron said in a rare television interview. "But there are not a hundred ways to balance the accounts ... this reform is necessary."

Until the government pushed the pension bill through without a vote, the protests against a bill extending the retirement age by two years to 64 had gathered huge, peaceful crowds in rallies organised by unions.

But since the government's decision to skip a vote in parliament last week, spontaneous protests in Paris and elsewhere have seen rubbish bins and barricades set ablaze every night amid scuffles with police.

Protesters on Wednesday also blocked train stations in the southern cities of Nice and Toulouse.

This, alongside with rolling strikes that affect oil depots, public transport and garbage collection, represent the most serious challenge to the centrist president's authority since the "Yellow Vest" revolt four years ago.

Macron said what he called "extreme violence" was not acceptable, while he respected the right to peaceful protests.

"We'll make sure a life that is as normal as possible can resume in the face of the few that block things," he said.

Neither a government reshuffle nor snap elections are on the cards, but rather an attempt to regain the initiative with measures to better involve citizens and unions in decision-making, political leaders in Macron's camp said ahead of the interview.

Polls show a wide majority of French are opposed to the pension legislation, as well as the government's decision to push the bill through parliament last week without a vote.

But Macron said he would stand firm.

"Between the short-term polls and the general interest of the country, I choose the general interest.... we will not tolerate any misbehaviour," he said. (Reuters)