"Sadly, we lost 229 of our compatriots to the COVID-19 infection” from Monday to Tuesday, Health Ministry spokeswoman Sima Sadat Lari said on Tuesday.
"This raises the overall toll to 14,634," she said in televised remarks.
Iran announced its previous record COVID-19 death toll of 221 on July 9.
Iran has been battling a resurgence of the virus, with official figures showing a rise in both new infections and deaths since a two-month low in May.
Lari also raised the country's caseload to 278,827, with 2,625 more people testing positive for the disease.
Of the new cases detected since Monday, 1,977 patients have been admitted to the hospital, she added.
At least 242,351 patients have recovered from the coronavirus infection so far or have been discharged from hospitals across Iran, the spokeswoman said.
Among those undergoing treatment in medical centers, 3,589 coronavirus patients have critical health conditions because of more severe infection, Lari noted.
She further said nearly 2,202,000 coronavirus diagnostic tests have been carried out in Iran so far.
Iran reported its first cases in the holy city of Qom in February.
The rising toll has prompted authorities to make masks mandatory in enclosed public spaces and to allow the hardest-hit provinces to reimpose restrictive measures, with Tehran included.
Iran closed schools, canceled public events and banned movements between its provinces in March, but gradually lifted restrictions from April to try to reopen its sanctions-hit economy.
Tasnim News Agency and AFP contributed to this story.