Iranian President Hassan Rouhani said Sunday mask-wearing will become mandatory in certain areas as the novel coronavirus deaths kept on rising.
The new steps were announced as the country recorded 144 new fatalities from the COVID-19, its highest death toll for a single day in almost three months.
Also, virus-hit provinces were allowed to reimpose restrictions.
Rouhani said Iran would have to live with the virus for the "long haul", as he announced the latest measures to combat it, AFP reported.
Mask-wearing would be "obligatory in covered spaces where there are gatherings", he said during a televised meeting of the country's anti-virus taskforce.
The measure would come into force as of next week, continue until July 22 and would be extended if necessary, he noted.
Rouhani also said the health ministry had devised "a clear list" of the types of spaces and gatherings deemed high-risk, but he did not elaborate.
He did not say what the penalty would be for those who fail to observe the measure.
According to deputy health minister Iraj Harirchi, services would not be provided to those without masks in areas such as government organisations and shopping malls.
But implementing the measure may be difficult, as according to Tehran's mayor, many do not wear masks in places like the capital's public transport network, where it is already mandatory.
"Fifty percent of metro passengers wear masks... and even fewer in buses," Mayor Pirouz Hanachi was quoted as saying by the semi-official ISNA news agency.
"We can't forcefully confront people without masks," he added.
Iran's health ministry on Sunday announced 144 virus deaths in the past 24 hours, its highest for a single day since April 5, raising the total to 10,508.
Spokeswoman Sima Sadat Lari also raised total confirmed infections to 222,669, with 2,489 new cases during the same period.
Iran closed schools, cancelled public events and banned movement between its 31 provinces in March, but the government progressively lifted restrictions from April to try to reopen its sanctions-hit economy.