About 150 heavy-goods vehicles and trailers disrupted traffic on roads near Reims, Sedan, Troyes and other eastern towns on Monday in protest at a proposal in next year's budget to end cheap diesel fuel for equipment used in construction and industry.
The measure, which the protesters say will mean a 60-percent rise, is part of a wider plan to increase taxes on all petrol, in particular high-polluting diesel, which is cheaper than unleaded petrol.
This year the price of diesel has risen 23 percent and that of petrol 15 percent.
In the 2019 budget the government is planning a rise of 6.5 centimes per litre of diesel and of 2.9 centimes per litre of petrol.
Thousands sign petition
A petition against the price rises had collected over 750,000 signatures at Monday midday and calls to stage go-slows in roughly 60 towns and cities on 17 November have gathered widespread support.
Two major supermarket chains, Leclerc and Carrefour, have announced they will be selling petrol at cost price for much of this month.
"It's the consumer who creates growth," commented Leclerc boss Michel-Edouard Leclerc on France Info radio. "This movement is legitimate."
An opinion poll last week showed 78 percent of the population agreeing with him.
No U-turn from Macron
But Macron is not backing down.
The price of diesel should be the same as the price of petrol, he declared on a trip to the sites of World War I battles on Monday. "I prefer taxing fuel to taxing work."
He went on to claim that "The same people who are up in arms about the fuel price rise also demand that we fight air pollution because their children are falling ill."
Economy Minister Bruno Le Maire had the same message.
"You don't suspend the ecological transition, the conversion of France's cars, which is necessary," he said, while promising to help people on low incomes.
Opposition condemns price rises
Opposition MPs have backed the protests, pointing to the effect they are expected to have on people living in rural areas and accusing Macron of being exclusively concerned with the metropolitan elite.
While opposing the call to block roads on 17 November, mainstream-right MPs Guillaume Peltier and Damien Abaud on Sunday slammed an "excessive rise in taxes" on diesel and proposed a 100-euro grant to 13 million people living in areas witjh poor public transport.
Le Maire has already dismissed that suggestion as a "short-term solution that would increase global warming".
The far-right National Rally, previously the National Front, has enthusiastically backed the movement.
Its leader, Marine Le Pen, promised that she and all the party's activists would take part in the protest "to tell the government the situation is becoming impossible".
Hard-left leader Jean-Luc Mélenchon also declared support for a "just and appropriate anger".
But, pointing to the involvement of "fascists" in promoting the 17 November protest, he refrained from openly endorsing it because "any attempt to politically exploit it will weaken the front that has been formed".
While fuel prices have indeed risen in France this year and will do so even more if the government's proposals go ahead, not all the increase is because of taxes, as many of the protest's supporters seem to believe.
The price of crude has risen worldwide - leading to a 35 percent this year for diesel and 28 percent for petrol.
That has dragged up VAT, which is now 20 percent on all goods and services.
A rise in an environmental tax this year has added to the increase but, in all, taxes are responsible for only about 26 percent of the total rise.
The discontent has also contributed to the fake-news plague on social media.
Rumours have circulated that placing a reflective jacket on your dashboard as a sign of support for the protest would be punished with a 150-euro fine, that Macron ordered the use of force to prevent "agitators" disrupting traffic, and that the head of the gendarmerie threatened to crack down on demonstrators.
They are all false, as is a claim that the police have expressed support for blockades on roads, boosted by an unknown hand adding the police service's logo to a post by an unofficial group of cops, which styles itself the Union of Independent National Police Officers.
Despite the rumours being debunked in the press, tempers have not subsided and France looks set for major disruption on the roads on 17 November.