French President Emmanuel Macron warned Sunday about far-right leader Marine Le Pen coming to power as he suggested that he should have got more involved in selling his unpopular pension reform to the country.

Speaking to Le Parisien newspaper, the 45-year-old joined others across the French political spectrum in warning about anti-immigration Le Pen being in a position to take power at the next presidential elections in 2027.

She is seen as the biggest political winner of the current turmoil in France sparked by Macron's decision to raise the retirement age, which has sparked three months of protests and strikes, as well as fears for the health of French democracy.

"Marine Le Pen will arrive (in power) if we are unable to respond to the challenges of the country and if we introduce a habit of lying or denying reality," Macron told the newspaper.

He has faced a hailstorm of criticism after forcing the pensions law through the lower house of parliament without a vote using a controversial constitutional power.

The increase in the retirement age to 64 from 62 is opposed by two-thirds of voters, according to polls, and did not appear to have a majority in parliament before Macron's government triggered article 49.3 of the constitution to ram it through.

Macron has kept a low profile since the start of the year, leaving Prime Minister Elisabeth Borne as the face of the reform.

"Perhaps the mistake was not being sufficiently present to give a substance to the reform and carry it myself," Macron added, while adding that he still had "confidence" in Borne whose job is seen as being on the line.

After signing the legislation into law earlier this month, Macron hit the road last week to meet voters in eastern and southern France where he was loudly booed and heckled.

Angry demonstrators pursued him and his ministers, banging saucepans through the week, an age-old French protest technique that is gaining in popularity.