Police fired tear gas at demonstrators in Paris and clashes broke out in other French cities on the 19 consecutive weekend of "yellow vest" protests against President Emmanuel Macron's government.

However, with military units deployed in Paris for the first time to back up police, the unrest did not match the scale of last Saturday when shops along the Champs Elysees avenue were looted and vandalised.

The demonstration in the capital was largely peaceful but later in the afternoon police fired tear gas on protesters near Boulevard de Strasbourg. Some protesters set bins on fire.

Clashes also took place in cities including Lille in northern France, Lyon, Nantes, Toulouse, Montpellier and Nice.

Demonstrators were banned from the Champs Elysees this Saturday and French Interior Minister Christophe Castaner said authorities had handled the latest protests well despite the flare-ups of crowd trouble.

"The correct methods have been applied, and the results are there to be seen," Castaner said in a televised address.

Even though they were banned from the Champs Elysees, demonstrators had gathered elsewhere to march from southern Paris, from where they crossed over the River Seine and ended up by the Sacre Coeur church in the north.

A yellow awning was briefly draped across the top of the Sacre Coeur, before being taken down by authorities.

Castaner said police had confiscated items such as baseball bats and masks from potential troublemakers.

Across France, 40,500 demonstrators turned up this Saturday, up from 32,300 last weekend, he said. In Paris alone, the number of demonstrators fell to 5,000 from 10,000.

The "yellow vests" protests, named after the high-visibility vests kept by French drivers in their cars and worn by protesters, began in November after public anger against fuel tax rises but the movement has morphed into a broader backlash against Macron's government, despite it scrapping the fuel taxes, and it has often been marred by violent clashes and looting.