Protestors help an injured man near the Champs Elysees avenue in Paris on December 8, 2018, during a mobilisation against rising costs of living they blame on high taxes. More than 30 people were injured.
Donning the luminous safety vests French drivers are required to carry in their cars, the protesters have blocked motorways and petrol depots since their first Saturday of demonstrations on November 17.
Three Associated Press journalists had gas masks and protective goggles confiscated by police despite carrying government-issued press cards.
But he also said there was a need to "re-establish national unity" and said President Emmanuel Macron would soon propose new measures to make this happen.
"According to the information we have, some radicalized and rebellious people will try to get mobilized tomorrow", Interior Minister Christophe Castaner told a news conference Friday.
"These past three weeks have seen the birth of a monster that has escaped its creators", he said, adding that a "large-scale" security operation would be launched Saturday.
He said the Louvre museum, Orsay museum, the two operas, and the Grand Palais were among the sites that would be closed a week after rioters looted and defaced the Arc de Triomphe.
Offshoot movements have emerged elsewhere, and yellow-vest protests were held Saturday in Belgium and the Netherlands.
Philippe on Friday evening met a delegation of self-described "moderate" yellow vests who urged people not to join the protests.
"We're asking him to meet us to negotiate on spending power, which is what underpins all this anger", Cauchy told AFP. "I hope he will speak to the people of France as a father, with love and respect and that he will take strong decisions", he said.
Authorities deployed barricade-busting armoured vehicles and 8,000 police in the capital alone.
While the protests began over fuel taxes, they have snowballed into a wider movement against Macron, largely among people in small-town and rural France.
Prized Paris monuments and normally bustling shopping meccas locked down and tens of thousands of police took position around France to face protesters angry at President Emmanuel Macron and France's high taxes.
Earlier in Brussels, police used pepper spray and scuffled with a small group of protesters who tried to break through a barricade blocking access to the European Parliament and the European Union's other main institutions.
Police and protesters also clashed in the southern French cities of Marseille and Toulouse.
Much of the city will effectively be on lockdown.
Shops, museums, the Eiffel Tower and many metro stations were closed, while top-flight football matches and concerts have been cancelled.
In a warning of impending violence, an MP for Macron's party, Benoit Potterie, received a bullet in the post on Friday with the words: "Next time it will be between your eyes".
As night fell, protesters converged on Place de la République, and a heavy police presence remained on the Champs-Elysées.
Eric Verhaeghe, an author, businessman, and political columnist, said that although wages have modestly increased, taxes have increased more and so people feel they're becoming poorer. "Take care of Paris on Saturday because Paris belongs to all the French people". "Protests and riots all over France", Trump said earlier on Saturday. Some protesters set fire to cars and smashed windows. Within days, many were simply calling for Macron to resign.
French students opposing changes in key high school tests protested again Friday, a day after footage widely shared on social media showed the arrest of protesting high school students outside Paris and prompted an outcry.
The 40-year-old former investment banker, dubbed "the president of the rich" by critics, has so far ruled out re-imposing the "fortune tax" on high-earners, arguing it is necessary to boost investment and create jobs.
As with many modern street movements, there is no leader or single clear aim.
On his return from the G20 summit in Argentina, Macron immediately calls a crisis meeting at the Elysee Palace on Dec 2.