Prime Minister Giuseppe Conte said on Saturday evening in a television speech that the government had chose to stop any production nationwide that was "not absolutely necessary, crucial and indispensable for basic services".
The request includes limitations to physical activity in offices and professional ones, closure of construction sites and further limitation in commercial activities.
Italy has the highest number of deaths from the new coronavirus and the second-highest total of cases worldwide.
And in neighbouring New York, Governor Andrew Cuomo warned that the disruption is likely to last for months, not weeks.
Authorities said most of the people who died had existing health problems such as heart disease and diabetes before they were infected with the virus.
"Let us do the things that the government asks us to do for the good of us all", Pope Francis said.
Italy has now reported more deaths than mainland China and third-placed Iran combined, and it has a death rate of 8.6 percent among confirmed COVID-19 infections - significantly higher than in most other countries.
During a television address to the nation, he said: "We will slow down the country's productive engine, but we will not stop it". Almost 20,000 people have been infected, becoming the second-worst-hit country in Europe.
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Spanish health authorities have acknowledged that some intensive care units in the hardest-hit areas are close to their limit.
"You have to shut down all economic activity, everyone has to stay at home", Sun Shuopeng, the group's vice president, said this week.
The virus, which emerged in Wuhan, China last December, has spread to at least 170 countries and regions around the globe, while the tally of confirmed cases topps 304,000, according to data compiled by US -based Johns Hopkins University.
As world leaders have vowed to fight the pandemic, the number of deaths and infections has continued to rise, especially in Europe - the main global hotspot.
Italy on Thursday overtook China as the country worst affect by the highly contagious virus.
The median time between the onset of the first symptoms and subsequent death was eight days, with the median time spent in hospital just four days.
"This virus can take them to the hospital for weeks or even kill them", said Tedros. Delhi was among several cities to ban all gatherings in the capital and more than a billion Indians across the country observed a one-day national curfew on Sunday.
Severe cases of coronavirus present like pneumonia, inflaming the lungs and filling them with fluid.