Iran registered a daily record 272 deaths from the coronavirus, the Health Ministry said on Monday, taking total fatalities to 28,816.
Ministry spokeswoman Sima Sadat Lari told national TV that 4,206 new cases were identified in the past 24 hours, with the total number of confirmed cases rising to 504,281.
She said some 409,000 people have so far recovered from the disease.
It was for the second day in a row that the ministry announced the highest single-day death toll from the virus.
Iran has seen the hardest outbreak in the West Asia. Health officials have warned about a third wave of the pandemic, with the government urging people to adhere to health protocols.
The situation in the capital Tehran has worsened, prompting officials to tighten restrictions earlier this month, shutting down universities, schools, libraries, mosques, cinemas, museums and beauty salons.
On Saturday, the government ordered all Tehran residents to wear face masks outdoors and in public places, and warned violators would be fined 500,000 rials, or $1.6.
Health Minister Saeid Namaki made an appeal on Sunday for harsher penalties, noting the meager fines for maskless residents would do nothing to boost vigilance.
Authorities are planning to make mask-wearing mandatory in public in other large cities.
As infections surged, government spokesman Ali Rabiei promised that those who tested positive would be closely tracked.
Reuters and AP contributed to this story.