Canada will be closing its borders to anyone who is not a citizen or a permanent resident, Prime Minister Justin Trudeau has announced.
The new measure to mitigate the spread of the coronavirus in Canada does not include US citizens.
Additionally, air operators will be "formally mandated' to prevent symptomatic travellers from boarding flights to Canada, Mr Trudeau said.
The prime minister said he has informed G7 partners of the new rules.
Only four Canadian airports - in Montreal, Toronto, Calgary, and Vancouver - will be accepting international flights beginning Wednesday.
"As the virus continues its spread, we've decided to take increasingly aggressive steps to keep you and your families safe," Mr Trudeau said.
Mr Trudeau said these "far reaching" measures will help save lives.
What is the situation in Canada?
Canada had at least 324 confirmed cases of Covid-19 across all 10 provinces as of Monday morning. There are an additional 17 presumptive cases.
Three new deaths linked to the virus were reported, bringing the total fatalities in Canada to four, all in the province of British Columbia.
Mr Trudeau addressed Canadians outside his residence. He is in self-isolation after his wife, Sophie, tested positive last week for the coronavirus.
Last week, Canada asked citizens to avoid all non-essential travel and urged travellers to return home where possible. All returning Canadians are being asked to self-isolate for two weeks.
What more did Canada announce on Monday?
The new measures on travel to Canada will be in place as of Wednesday, 18 March, officials said.
Mr Trudeau said there will be an assistance programme implemented for asymptomatic Canadians abroad to help them pay for their return, if needed, or to help them with basic needs as they wait to come home.
"If you're abroad, it's time for you to come home," the prime minister said.
He also said flow of trade and commerce will not be affected by these latest border restriction steps.
Asked why United States citizens were exempt from the latest measures, Mr Trudeau said the country is working closely in its efforts with the United States.
The Canada-US border is highly integrated with significant trade and people crossing daily, he said.
This "puts the US in a separate category from the rest of the world".
The federal government had previously said closing borders was not required, but Mr Trudeau said it was now "the time to take this particular step".
A number of countries have announced similar measures, including Germany and France.
The United States had already implemented sweeping travel restrictions on many European nations and most recently Ireland and the UK.
Provinces take additional steps
Some provinces and cities have implemented their own measures to prevent contagion.
A number of provinces have temporarily closed public schools, as have the Northwest Territories and Nunavut.
Over the weekend, Quebec - where there are approximately 39 cases - asked establishments such as bars, cinemas, arenas, spas and gyms to close indefinitely. Restaurants were asked to operate at 50% capacity.
Amid reports that people returning to Canada had not been advised to take appropriate self-isolation measures, Montreal authorities said they will be sending additional public health teams and police at the Pierre Elliott Trudeau International Airport to ensure all travellers are informed.
Health officials in Toronto, Canada's largest city, are now "strongly recommending all bars, dine-in restaurants, nightclubs, and theatres close" as of midnight.