Police have detained one of the leaders of France’s gilets jaunes anti-government movement for organising an unauthorised protest, as authorities adopt a tougher approach to try to curb the demonstrations.

Eric Drouet, a lorry driver, already faces trial in June for “carrying a prohibited category D weapon”, after he was allegedly found with a wooden stick at a previous protest.

He was arrested by police on Wednesday night as he was heading towards the Champs Élysées in Paris, where several demonstrators had been waiting for him. They said they intended only to light candles for the people injured during demonstrations or killed in road accidents during the six weeks of protests on roads and roundabouts, which began in November as a fuel tax revolt but morphed into a movement against the president, Emmanuel Macron, and policies seen to favour the rich.

Drouet’s lawyer called the arrest “totally unjustified and arbitrary”. He said Drouet had intended to lay candles at Place de la Concorde in Paris then meet others in a private place.

The economy minister, Bruno Le Maire, defended Drouet’s arrest, saying: “It’s called respecting the rule of law ... It’s normal that when you break the laws of the republic, you face the consequences.”

Since 17 November, the gilets jaunes – or “yellow vests”, named after their fluorescent jackets – have regularly held demonstrations that were not declared to the authorities. For several weekends, demonstrations in Paris and other cities such as Toulouse and Bordeaux saw violent skirmishes with police as well as banks and shops smashed up and cars burned.

The authorities now appear to be clamping down on the continuing protests. The interior ministry wrote to local police chiefs this week saying the rural and suburban roundabouts and toll booths that have been occupied for weeks should be cleared of protesters.

Some said the arrest of Drouet, often seen on TV as a gilets jaunes spokesman, could turn him into a sort of martyr figure and harden the resolve of demonstrators.

The leftwing leader Jean-Luc Mélenchon, a fierce critic of Macron, tweeted: “Again Eric Drouet arrested, why? Abuse of power. A politicised police targeting and harassing the leaders of the yellow vest movement.”

Benjamin Cauchy, another gilets jaunes media figure who takes a more moderate line on the protests, said after Drouet’s arrest: “Unfortunately I have the impression that the government wants to radicalise the movement. The executive is pouring oil on the fire. They’ve just put another coin in the jukebox and the gilets jaunes song is going to go on playing, that’s for sure.”

In a separate development, Macron’s head of media relations, Sylvain Fort, announced that he was leaving for “personal reasons”. Fort, an opera buff and expert on classical literature, remains one of Macron’s closest inner-circle. He had preferred his long stint as Macron’s chief speech-writer to the communications role and his departure was not a total surprise. But it raised the question of whether the gilets jaunes movement and the continuing scandal around Macron’s former bodyguard and security advisor, Alexandre Benalla, has begun to wear down the president’s small group of loyal aides. Fort’s replacement as head of Macron’s media operation has not yet been announced.