US President Donald Trump announced the new levies in a brief statement on social media, responding to a violent crackdown on protests in the Middle Eastern dictatorship which has left hundreds dead.
"Any country doing business with the Islamic Republic of Iran will pay a Tariff of 25 per cent on any and all business being done with the United States of America," Mr Trump said on his Truth Social platform on Tuesday morning, Australian time.
While the federal government has sanctions imposed on the Iranian regime, there was still more than $700 million in two-way trade between Australia and Iran in 2024, according to the Department of Foreign Affairs.
Government sources said they were seeking advice on Mr Trump's announcement, but pointed out the US also trades with Iran.
Officials believed the final text of the American trade restrictions could differ from the president's initial announcement.
Trade Minister Don Farrell said he needed to see more detail about what Mr Trump was proposing.
"... we need to have a look at that. That's a very recent announcement," he told reporters in Adelaide on Tuesday.
As the death toll from anti-government protests in Iran rises, Prime Minister Anthony Albanese said the Iranian supreme leader should be "removed by the people".
More than 500 Iranians have been killed in the demonstrations according to human rights groups, but some activists believe the true number of fatalities may run into the thousands.
Dozens of security personnel have also died and thousands of protesters have been arrested.
Mr Albanese said the Iranian government was an "oppressive regime" which should be replaced by democracy.
"We stand with the people of Iran in fighting against what is an oppressive regime, one that has oppressed its people. One that is, I hope ... removed by the people," he told reporters at Parliament House on Tuesday.
Foreign Minister Penny Wong said Iran's crackdown on protests had become increasingly brutal as Ayatollah Ali Khamenei tried to retain power.
"What I would say to that regime is, not only is the world calling on you to stop killing your people, but a regime that requires the murder of its own people to maintain authority is not a regime with any legitimacy," she said.
Mr Trump has said he would "be hitting them very hard where it hurts" if Iran began killing demonstrators like it did in the past, but is yet to declare military action.
In response, Iran has said it is "prepared for war", but also willing to negotiate with American officials.
Members of Australia's Iranian community say they are feeling numb and helpless as they watch from afar while the death toll from the protests rises.
Australian-Iranian Community Organisation president Siamak Ghahreman said many had struggled to contact family back home because of an internet blackout, cutting the nation off from the rest of the world.
"This is really sad and the whole community is numb, plus there isn't much people can really do from here," he told AAP.
"We've done demonstrations and sent letters to the government, but that's as far as we can take it. It's been like that for 47 years.
"There is no common sense in the Iranian government and for it to survive, they are prepared to kill as many as it takes just to be in power."
