TEHRAN — President Hassan Rohani appealed on Wednesday for "unity" and flagged the need for radical changes to the way Iran is run, after a wave of angry protests over the accidental downing of a Ukrainian airliner.

The Kiev-bound Boeing 737 was shot down in a catastrophic error shortly after takeoff from Tehran, killing all 176 people aboard.

One week on from the disaster, Rohani called for "national unity" in remarks broadcast live on state television.

"If there was a delay" by the armed forces to release information about the air disaster, "let them apologize," he said.

Rohani also sought a full explanation after it took Iran days to admit the airliner had been mistakenly shot down.

The blunder sparked four consecutive nights of protests in Tehran calling for those responsible to resign or be prosecuted, leading to at least 30 arrests.

Iranian Foreign Minister Mohammad Javad Zarif said they were demonstrating after being deceived for days.

"In Iran... people can state their views. Sometimes they state their views in excessive ways, sometimes the reaction is excessive," he said in New Delhi.

"But the fact of the matter is, (over the) last few nights we've had people in the streets of Tehran, demonstrating against the fact that they were lied to for a couple of days."

The latest protests have been much smaller than nationwide demonstrations against fuel price hikes in November that Amnesty International said left more than 300 dead in a crackdown by security forces.

The Ukraine International Airlines plane was downed with Iran on high alert hours it fired a volley of missiles at US troops stationed in Iraq.

The attack on Iraqi bases was launched in retaliation for a US drone strike that killed Qasem Soleimani, the top commander of the Iranian Revolutionary Guards' foreign operations arm.

Rohani also said Iranians wanted "diversity" as he urged the electoral authorities to refrain from disqualifying would-be candidates for a Feb. 21 general election.

That would mark a major shift in a country where all candidates are vetted for their loyalty by constitutional watchdog the Guardian Council.

"The people are our masters and we are its servants," Rohani said.

"Allow all parties and groups to run for office," he said. "Surely you have nothing to lose.

"The country cannot be governed by one political wing alone."

Iran has been rocked by crisis after crisis since 2018.

In May that year, US President Donald Trump unilaterally withdrew from a landmark 2015 agreement that gave Iran relief from sanctions in return for curbs on its nuclear program.

Since then, the US has relentlessly slapped waves of sanctions on Iran as part of a "maximum pressure" campaign.

Washington says the campaign is aimed at reining in Tehran's missile program as well as its "destabilizing behavior" in the region.

Iran has hit back by progressively reducing its nuclear commitments.

On Tuesday, as tensions mounted over the downed airliner, European parties to the deal launched an arbitration process charging Iran with failing to observe its commitments to the accord.

Iran warned Britain, France and Germany they must "be prepared to accept the consequences" of their move.

The past year has seen arch-enemies Tehran and Washington come to the brink of war on at least two separate occasions.

Rohani blamed the Americans and their allies for causing "insecurity" across the Middle East.

Their "mistakes", he said, included Soleimani's killing, interventions in Iraq, Libya and Yemen, and the US decision to pull out of the nuclear deal and reimpose sanctions on Iranian oil.

"Security in this sensitive and important region will come at the expense of the entire world," said Rohani.

"Today the American soldier is not safe, tomorrow it could be the turn of the European soldier," he added, warning the US and its allies to leave the region.

The downing of the plane came after a spate of disasters for Iran.

On Jan. 7, at least 59 mourners were trampled to death at a funeral procession for Soleimani.

Iran has also been hit by flooding since Friday that has claimed at least three lives.

Referring to the disasters, Rohani said they should lead to a "big decision" about Iran's political system.

"And that major decision," he said, "is national reconciliation."

"These (parliamentary) elections must be the first step."

In 2017, supreme leader Ayatollah Ali Khamenei rejected the possibility of "national reconciliation".

The idea, which called for more pluralism, had been presented at the time by reformists as a way to heal wounds left over from the disputed 2009 re-election of president Mahmoud Ahmadinejad. — AFP