Iran's Rouhani urges 'unity' after plane protests

President Hassan Rouhani appealed 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 last week in a catastrophic error shortly after takeoff from Tehran, killing all 176 passengers and crew on board.

Iran had for days denied claims based on US intelligence that the plane had been downed by a missile, triggering four days of demonstrations as well as international calls for a full and transparent investigation.

One week on from the disaster, Rouhani called for "national unity" in an address broadcast live on state television.

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

Rouhani also called for a full explanation of what happened in the air disaster, which came hours after Iran's military fired a wave of missiles at US troops stationed in Iraq.

The missile attack was launched in retaliation for a US drone strike that killed Iran's most prominent general, Qasem Soleimani, who headed the Revolutionary Guards' foreign operations arm.

Rouhani also said Iranians wanted "diversity" as he urged the electoral authorities to refrain from disqualifying would-be candidates for a February 21 general election. That would mark a major shift in a country where all candidates are vetted by a constitutional watchdog, The Guardian Council, for their loyalty to the state.

"The people are our masters and we are its servants. The servant must address the master with modesty, precision and honesty," Rouhani said in his remarks after a cabinet meeting.

"The people want to make sure that the authorities treat them with sincerity, integrity and trust.

"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. The country belongs to everyone."