While state television showed long queues at polling stations in several cities, the semi-official Fars news agency reported 22 million or 37% of voters had cast ballots by 7:30 p.m. (1500 GMT), citing its own reporter. The interior ministry said it could not confirm turnout figures.
Iran's clerical and military rulers have threatened revenge for Friday's killing of Mohsen Fakhrizadeh, which could further increase tensions in the Middle East region and beyond.
“Education will not be closed in our country even under the worst situation,” President Hassan Rouhani said, urging authorities to implement health measures in schools to the level of those in military garrisons.
In his televised speech, Rouhani warned the UAE against allowing Israel a 'foothold in the region'.
The figures President Rouhani cited in a televised speech were far higher than Saturday's official toll of 271,606.
The figures, which Rouhani said were based on a new Health Ministry report, are far higher Iran's official toll of 269,440 infected. Rouhani in a televised speech did not address the discrepancy.
The head of Iran's elite Revolutionary Guards said on Thursday that Tehran would destroy US warships if its security is threatened in the Gulf, a day after US President Donald Trump warned Tehran over "harassment" of US vessels.
"It was a great opportunity for Americans to apologise ... and to lift the unjust and unfair sanctions on Iran," Hassan Rouhani said in a televised cabinet meeting.
Relations between Tehran and Washington reached crisis point in 2018 after U.S. President Donald Trump abandoned a 2015 pact between Iran and world powers under which Tehran accepted curbs to its nuclear programme in return for the lifting of sanctions.
Iran's clerical rulers face challenges in keeping the economy afloat under increasingly tough US sanctions imposed by Washington after it withdrew in 2018 from Tehran's nuclear deal with world powers
"The people want to make sure that the authorities treat them with sincerity, integrity and trust," said Rouhani, also calling on the armed forces to "apologise" and explain what happened in the air disaster.
"There is no doubt that the great nation of Iran and the other free nations of the region will take revenge for this gruesome crime from criminal America," Rouhani said in a statement posted on the Iranian government website.
The trip comes after violent protests last month over petroleum price hikes in Iran, as Washington-imposed sanctions over its nuclear programme hit the Iranian economy.
Khan, who visited Tehran on Sunday to help mitigate tensions between bitter regional rivals Iran and Saudi Arabia, held talks with President Rouhani at the presidential palace and later met with Iran's supreme leader Ayatollah Ali Khamenei.
The Islamic republic is prepared "to hold fruitful negotiations", he told the Iranian cabinet, referring to two days of diplomatic efforts by French President Emmanuel Macron.
Ryabkov told reporters that Moscow had repeatedly warned Washington and its regional allies about what he called the 'unthinking and reckless pumping up of tensions in an explosive region.'
Rouhani's remarks could also be seen as a defense of his stance following the rare public chastising by the supreme leader.
Rouhani warned of a firm response if Iran's nuclear case is referred again to the United Nations Security Council, but said Tehran was ready for negotiations over its nuclear programme.
A report said that the decision to name Touraj Zanganeh the CEO of the airline was made during a Cabinet meeting on May 5.
If the United States is able to stop one method for Iran to export oil, then it will find other ways, Rouhani said.
Iraq invaded Kuwait in 1990, which resulted in the seven-month-long Iraqi occupation of the country.
The bill also demands the Iranian government take unspecified action against other governments that formally back the US designation.
Speaking at a ceremony to mark Iran's national nuclear technology day in Tehran, Rouhani defended the Revolutionary Guards as a force that has fought terrorism ever since its creation in 1979.
Kambiz Mehdizadeh, in his early thirties and reportedly married to Rouhani's daughter in a low-key wedding this August, was appointed to the senior position in the industries and mining ministry on December 15.
US officials have said they intend to reduce Iran's oil exports to zero in an effort to curb the Islamic Republic's missile program and regional influence.