"Today, we see that a movement that began peacefully on Saturday has turned violent," French Interior Minister Christophe Castaner told French TV channel France 2.
"We are now dealing with radicalisation, with claims which are no loner coherent, and which are all over the place," he said.
Protesters angry over high fuel prices have blocked access to fuel depots and stopped traffic on major roads since Saturday, vowing to continue their movement until the government backs down on fuel taxes.
One person was accidentally killed at the start of the protests and 528 people injured, 17 seriously. Among them, are three police officers who were reportedly struck with pétanque balls.
"The right to demonstrate (...) does not give you the right to obstruct, to impose your will, or to injure security forces," Castaner added, stating that there have been "as many security officers injured in four days than during the evacuation of the Notre-Dames-des-Landes site in April."
In April, police moved to evacuate tenacious squatters opposed to the construction of an airport in Western France.
Consequences for demonstrators
"From now on there will be identity checks and fines," the French interior minister warned, inviting "those people who are peaceful, not to allow themselves to be carried away by those who are more radical, and to remain within the boundaries of the law."
On Monday, tens of thousands of demonstrators were still manning hundreds of barricades on motorways and petrol stations, down from nearly 300,000 protesters at over 2,000 sites on Saturday.
Oil giant Total confirmed that some of its trucks had been prevented from reaching depots in the south and east of the country, causing alarm among small business owners.
"It is important to bear in mind that our security forces are best able to guarantee the security of our citizens when they do not have to anticipate or run after people who block round-abouts," Castaner affirmed.
The Yellow Vest movement -- named after the high-visibility vests motorists are required to carry in their cars -- was sparked by rising diesel prices, which many blame on taxes implemented in recent years as part of France's anti-pollution fight.
It quickly snowballed into a protest by rural and small-town France over falling spending power of the less well-off under Macron, assailed as a "president of the rich".
Prime Minister Edouard Philippe said Sunday night that the government had heard the protesters' anger but would not change course.