Health ministry spokesman Kianoush Jahanpour said on Monday that 74 new fatalities brought to 6,277 the total number officially recorded in Iran since mid-February, when it first reported cases of COVID-19, the disease caused by the virus.
Another 1,223 cases of COVID-19 infections were recorded in the past 24 hours, Jahanpour said, raising the total to 98,647.
Mosques were allowed to reopen to worshippers in 132, or around a third, of Iran's administrative divisions which are considered low-risk.
The country has started using a colour-coded system of "white", "yellow" and "red" for different areas to classify the virus risk.
Worshippers were obliged to enter mosques with masks and gloves and told they could only stay for half an hour during prayer times, said the health ministry.
Mosques were told to refrain from offering them food and drinks, provide hand sanitisers and disinfect all surfaces, it said in a statement published by ISNA news agency.
According to Jahanpour, 79,397 of those hospitalised with the disease since Iran reported its first cases in mid-February have been discharged, while 2,676 are in critical condition.
He said Iran was among "top five countries in the world" with the highest number of recoveries, without elaborating.
Experts and officials both in Iran and abroad have cast doubts over the country's COVID-19 figures, saying the real number of cases could be much higher than reported.
President Hassan Rouhani said Iran had "succeeded in effectively preventing the spread of this virus in many" parts of the country.
Speaking at a televised videoconference meeting of the Non-Aligned Movement, Rouhani said Iran's response to the outbreak "has in instances been evaluated to be beyond international standards."
But the US "anti-human rights" sanctions against the Islamic republic had hampered its efforts to control the virus, he added, noting that they prevented companies from selling Iran its medical needs.
US President Donald Trump withdrew from a landmark nuclear deal and reimposed unilateral sanctions on Iran in 2018, targeting key oil and banking sectors.
Humanitarian goods, especially medicine and medical equipment, are technically exempt.
But international purchases of such supplies are forestalled by banks wary of conducting any business with Iran for fear of falling foul of the US sanctions.