Nigeria will begin a “gradual easing” of coronavirus-related lockdowns in the federal capital territory of Abuja, and Lagos and Ogun states from 4 May.
The lockdowns had been due to end on Monday night, but President Muhammadu Buhari said they needed to continue.
He also ordered new nationwide measures against Covid-19, including a night-time curfew and mandatory face masks.
The moves would ensure the economy functioned “while still maintaining our aggressive response”, Mr Buhari said.
Earlier, workers at a construction site in Lagos rioted in protest at the lockdown.
A police spokesman said the workers at the Lekki Free Trade zone – including those at the oil refinery of billionaire Aliko Dangote – went on the rampage and injured several officers in the area. Fifty-one people were arrested, he added.
There are reports that the protesters were angry that some foreign nationals were allowed to go to work at the site.
Nigeria, Africa’s most-populous nation and largest economy, has reported 1,273 confirmed cases of Covid-19 and 40 deaths.
In a televised address on Monday night, Mr Buhari acknowledged that the lockdowns in Abuja, Lagos and Ogun had “come at a very heavy economic cost” since they began on 30 March.
“Many of our citizens have lost their means of livelihood. Many businesses have shut down,” he said.
He added: “No country can afford the full impact of a sustained lockdown while awaiting the development of vaccines.”
The president said there would therefore be a “phased and gradual easing” of the lockdowns next Monday to allow some economic activities to resume.
But to limit the spread of Covid-19, he announced that the government would impose a curfew across the country between 20:00 and 06:00, require everyone to wear face masks in public, and stop “non-essential inter-state passenger travel”.
Bans on social and religious gatherings will also remain in place.
Mr Buhari also expressed deep concern over the unexplained deaths of a number of people in the northern state of Kano.
He said a lockdown would be imposed there for two weeks with immediate effect and that he was sending a government team to investigate.