He told reporters in Canberra do not go overseas, that is very clear, that instruction.
"If you are overseas and can not, or do not want to, return to Australia, follow the advice of local authorities", it added.
"Regardless of your destination, age or health, our advice is do not travel at this time", the government's travel advisory website states.
A ban on non-essential indoor gatherings of more than 100 people is effective immediately.
Schools, universities, childcare facilities, airports, public transport, medical and emergency services facilities, aged care homes, accommodation facilities, jails, courts, parliaments, supermarkets and many workplaces are exempt.
"All people coming to Australia will be required, will be required, I stress, to self isolate for 14 days", Morrison said on Sunday.
Australia has recorded over 450 positive tests and five deaths, with a sharp rise in cases in the past week.
But people should practice social distancing in all these areas, keeping a space of 1.5 metres between themselves and others.
He also says schools will remain open for now, despite growing concerns around the country. "The Australian Government may not be able to help you".
"We are going to keep Australia running". There is no short-term, quick fix to how this is dealt with in Australia.
Australia joined neighbouring New Zealand Wednesday in urging citizens overseas to return home promptly or risk being stranded in an ominous sign they expect flights to the remote South Pacific nations may shut down entirely.
The Federal Government has warned the economic downturn from the outbreak will see Australians lose their jobs and businesses close down.
"The travel advice to every Australian is 'Do not travel overseas, '" Morrison announced at Parliament House.
Morrison has already flagged a stimulus package worth around A$17 billion and said on Wednesday the government was "considering quite extensive further economic measures" to tiresome the impact on the economy.
"If we slow the spread, then we do save lives".
A spokesman for national carrier Qantas said it would continue issuing tickets to Australians wanting to leave the country.
Morrison called the coronavirus pandemic "a once-in-100-year-type event".
"It is important that we, who are healthy, those of us who will contract this and have experience of a mild illness, that we do what we can to limit the spread to ensure that those who are more vulnerable are not affected", he said.
Updated travel advice from the Department of Foreign Affairs and Trade is urging Australians overseas wishing to come home to do so as soon as possible, as coronavirus fears spread.