US President Donald Trump, asked what he meant by a social media post saying "help is on its way" to protesters in Iran, told reporters that they would have to figure it out.

"You're going to have to figure that one out. I'm sorry," Trump said in response to a question on Tuesday.

Trump also told reporters that nobody has been able to give him an accurate number for how many protesters have been killed in recent demonstrations.

Earlier, Trump called on Iranian demonstrators to keep “protesting and take over institutions, saying, “help is on its way,” while warning that Tehran officials will pay a high price.

“Iranian patriots, keep protesting, take over your institutions!!! Save the names of the killers and abusers. They will pay a big price,” Trump posted on Truth Social.

He further stated that he had cancelled all his meetings with Iranian diplomats.

“I have cancelled all meetings with Iranian officials until the senseless killing of protesters stops. Help is on its way. MIGA!!!”

Trump was using an acronym that is a play on his Make America Great Again slogan, referring instead to Iran.

On Monday, the White House said the US president "has an interest" in exploring diplomacy with Iran.

Spokesperson Karoline Leavitt said that Trump is "unafraid" to follow through on his threats to use military force on Iranian targets if demonstrators are attacked by security forces, but said his preference is to pursue diplomacy with Tehran.

Iranian officials have accused the US and Israel of backing what they describe as "armed rioters," who have carried out several attacks in public places nationwide.

There are no official casualty figures, but a US-based rights group estimates that the death toll has reached at least 646, including both security forces and protesters, with over 1,000 injured.

The rights group also reported that at least 10,721 people have been detained across protests in 585 locations nationwide, including 186 cities in all 31 provinces.