Iran recorded 107 deaths in the past 24 hours, taking the total to 8,837. The total number of cases in the country has reached 187,427.
"Today it was very painful for us to announce a triple digit statistic... this virus is unpredictable and shifting," Health Ministry spokeswoman Sima Sadat Lari said on state TV.
"Observe health protocols, take social distancing seriously, avoid gatherings and trips that aren’t essential and, God willing, in the coming days we will see the statistic come down into double digits and even single digits."
Iran last announced more than 100 deaths in one day on April 13, when the tally was 111.
Iran will reimpose restrictions to stem the surge in coronavirus cases if health regulations are not observed, President Hassan Rouhani said on Saturday.
After gradually relaxing its lockdown since mid-April, Iran has seen a sharp rise of new daily infections in recent weeks.
Seven provinces where infections have been on the rise are currently considered red zones, the health ministry says.
On Sunday Rouhani accused the United States of attempting to block Iran's request to the International Monetary Fund for $5 billion in emergency funding to help fight the coronavirus outbreak."We are hopeful that the (IMF) is not put under America's pressure and will act according to its commitments to all countries," he said in comments broadcast on state TV.