Thousands of people joined May Day protests across France on Sunday to demand social justice and salary increases and to push newly re-elected President Emmanuel Macron to drop his plan to raise the retirement age.

Most rallies were peaceful but in Paris police intervened after black-clad "Black Bloc" anarchists tried to erect a barricade in a street near La Republique Square, police said. A McDonald's restaurant and a real estate agency on the Place Leon Blum were also ransacked, their windows broken and garbage bins set on fire.

The cost of living was the main theme in the presidential election campaign and looks set to be equally prominent ahead of June legislative elections that Macron's party and its allies must win if he is to be able to implement his pro-business policies, including increasing retirement age to 65 for 62

About 250 rallies were organised in Paris and other cities including Lille, Nantes, Toulouse and Marseille.

In the French capital, trade unionists were joined by political figures - mostly from the left - and climate activists.

Marchers carried banners reading "Retirement Before Arthritis", "Retirement at 60, Freeze Prices" and "Macron, Get Out"

"The stronger the mobilisation for this May Day, the harder we will be able to weigh on the government's policies," Philippe Martinez, the head of the hardline CGT union, told Reuters before the rallies.

"The government has got to deal with the purchasing power problem by raising wages," he said.

Macron won a new five-year presidential term after beating far-right challenger Marine Le Pen in last Sunday's runoff vote.

Far-left leader Jean-Luc Melenchon, who came third in the first round of the presidential vote, was attending the Paris march.

He wants to rally a union of the left, including the Greens, to dominate parliament and force Macron into an awkward "cohabitation" but so far this has not materialised.

"We will not make a single concession on pensions," Melenchon said before the march started.

He said he still hoped an agreement to build a new "popular union" of the left could be reached by this evening.

Unlike in previous years, Marine Le Pen did not lay a wreath in Paris at the statue of Joan or Arc, whom her party uses as a nationalist symbol. She was replaced by the Rassemblement National Interim President Jordan Bardella, who said Le Pen was preparing for the legislative elections.

Le Pen urged voters in a video message to elect as many deputies from her party as possible in June so that she could "protect your purchasing power," and prevent Macron from carrying a "harmful project for France and the French people"

France will hold parliamentary elections on June 12 and 19.