President Emmanuel Macron on Monday staunchly defended his widely unpopular pension reform but said he regretted that no consensus had been found on the change.

Addressing France for the first time since signing the reform into law, Macron said he understood the "anger" felt by the French over the raising of the retirement age.

Macron signed the legislation early Saturday, just hours after its banner change to hike the retirement age from 62 to 64 had been validated by the constitutional court, prompting accusations he was smuggling the law through in the dead of night.

After three months of protests and strikes, the left and unions have vowed not to give in and warned of mass Labour Day protests on May 1.

Polls have consistently recorded a majority of French opposed to the reform, which the government rammed through parliament using a controversial mechanism to avoid a vote.

Speaking from the Elysee Palace, Macron defended the reform as "necessary" and insisted "doing nothing" was not a solution.

"Has this reform been accepted? Obviously not. And despite months of consultations, no consensus could be found and I regret it."

Noting the protests that have raged against the reform, he added: "No one, especially not me, can remain deaf to this demand for social justice."

"The answer can be neither in rigidity, nor in extremism," said the president, adding his "door will always be open" to talks with the unions.

Macron's personal popularity ratings have eroded with some analysts suggesting he has given a head start to far-right leader Marine Le Pen down the long path to 2027 elections.

'No point in listening'

Unions have meanwhile spurned an invitation to the Elysee for talks.

As the president spoke, thousands gathered outside town halls across France, banging saucepans in a bid to drown out the speech.

"He hasn't listened to us for three months. We're doing this to show there's no point in listening to him either," 57-year-old projectionist Benedicte Delgehier said in Paris.

After the speech, dozens joined a spontaneous protest in the capital, setting fire to garbage containers with police firing tear gas canisters to disperse them, AFP correspondents said.

Opponents from across the board said Macron's speech had only reinforced concerns about how the reform was handled.

"He chose to turn his back on the French and ignore their suffering," said far-right figurehead and former presidential candidate Marine Le Pen.

Hard-left leader Jean-Luc Melenchon said Macron was "totally out of touch with reality".

CFDT union leader Laurent Berger added that it contained "nothing concrete" for the labour movement and said Macron had "not uttered a word" on easing tensions.

Possibly more troublingly for the president, the head of the right-wing Republicans who supported the reform, Eric Ciotti, dismissed the speech as a "catalogue of pious wishes" and said Macron's "method had clearly not changed".

Macron said he had tasked his government led by Prime Minister Elisabeth Borne to lead 100 days of action "at the service of France".

'Within slapping range'

The prime minister should lay out a roadmap in the next days with the first results to be announced on France's national day on July 14, Macron said.

He promised "major announcements" during May including action against juvenile delinquency and also "reinforcing controls against illegal immigration".

Macron earlier had lunch with Borne, then met key figures from his party including ultra-loyal rising stars tipped for promotions such as Defence Minister Sebastien Lecornu, 36, and Budget Minister Gabriel Attal, 34.

But no cabinet reshuffle is planned in the near future, several sources close to the presidency told AFP.

The president, often consumed with diplomacy, will this week also make at least one trip within France after criticism that he is failing to connect with people.

"I want Macron to spend more time on the ground," said one cabinet minister, who asked not to be named. Even "within range of being slapped".

The crisis also comes at a time of increasing challenges on the international stage for Macron, who faced accusations of cosying up to China on a visit to Beijing.

Macron, 45, came to power in 2017 promising reform and a fresh new politics. But opponents accuse him of increasingly reclusive and anti-democratic behaviour.

"Emmanuel Macron is far from finished from having to deal with the social and political crisis, which he continues to dangerously stir up," said Le Monde newspaper in an editorial.