President Emmanuel Macron criticised French people who had not taken restrictions on movement seriously and announced a range of further public health measures to stop the spread of COVID-19.
In a speech on Monday night, Macron said "we are at war," before urging the country to remain at home for 15 days to prevent coronavirus from spreading any further in France.
As well as a raft of new restrictions on people in France, Macron announced that the borders to the EU would close at midday on Tuesday 17 March for 30 days.
Just days after the country had already closed bars and restaurants, Macron also postponed the second round of local elections, set for Sunday, March 22.
It comes as Public Health France announced there had been 1,210 new coronavirus cases and 21 deaths in just 24 hours.
"We are at war, certainly a health war," said Macron. "We are not fighting against an army or against another nation. But the enemy is there, invisible, elusive, advancing. And this requires our general mobilisation."
Meanwhile, an army hospital in Alsace, eastern France, will be used in the coming days in the country's fight against coronavirus.
The new measures will be reinforced by 100,000 police and punishable by a 38€ which will quickly be increased to a 135€ fine, interior minister Christophe Castaner specified after the president's speech.
People can only go out with a downloadable certificate that states the reason why they are leaving the house.
People can only leave the house for work (where working from home is not an option), buying food or medicine, seeing a doctor, or urgent family needs such as bringing children to another parent or taking care of vulnerable adults.
They will also be allowed to exercise alone in the vicinity of where they live.
On Saturday, French Prime Minister Édouard Philippe said all bars, restaurants and non-essential shops must close to help contain the virus.
But Macron said on Monday that some had gone to park and restaurants, flouting the ban.
Urging people to stay indoors and work from home, he said the coronavirus outbreak was an "immediate reality".
Macron also announced rents and gas, water and electricity bills would be suspended. No French citizen would be left without resources, he added.
He announced €300 billion in fiscal support to companies that would lose business during the crisis.