Any US-led strike on Iranian targets would be fraught for a region bristling with tensions. Israel would have reason to be anxious about retaliation, given Iran rejects Israel's right to exist.

That said, Israel's Prime Minister Benjamin Netanyahu in April invoked the so-called "Begin Doctrine" that calls on the Jewish state to ensure nations hostile to Israel be prevented from developing a nuclear weapons capability.

"Israel will not allow regimes that seek our annihilation to acquire nuclear weapons," Mr Netanyahu said.

An Australian Government source said when it came to Iran, Australia relied on intelligence sourced from its Five Eyes partners, not Israel.

While some in the Turnbull Government firmly believe Mr Trump is prepared to use military force against Iran, others maintain it might be more bluster, given the consequence of conflict with Tehran might include unpredictable, dangerous responses in the Middle East.

Earlier this week, Mr Trump fired off an all-caps tweet directed at the Iranian President, seemingly warning of war:

He was responding to Mr Rouhani, who was quoted telling Iranian diplomats: "America should know that peace with Iran is the mother of all peace and war with Iran is the mother of all wars.

"Do not play with the lion's tail or else you will regret it," he said.

Mr Trump has since adjusted his rhetoric, suggesting Washington is ready to go back to the negotiating table with Tehran for a new nuclear deal.

"I withdrew the United States from the horrible one-sided Iran nuclear deal, and Iran is not the same country anymore," he told a convention in Kansas City.

"We're ready to make a deal."

Grappling with whether Mr Trump's Twitter missives should be believed has become a global quest — and not just his tweets about Iran or North Korea.

In response to the US President's all-caps tweet on Monday, a high-ranking Iranian army official told the ISNA news agency, a Tehran Government mouthpiece, that Mr Trump's threats were merely "psychological warfare".

General Gholam Hossein Gheibparvar, the chief of the paramilitary Revolutionary Guard's volunteer Basij force, said Mr Trump "won't dare" take military action against Iran.

It was an assessment echoed by Iranian MP Heshmatollah Falahatpisheh, who told Associated Press he doubted the escalating rhetoric would lead to a military confrontation.

Foreign Minister Julie Bishop has emphasised diplomatic efforts to bring Iran to heel.

"Australia is urging Iran to be a force for peace and stability in the region," she told ABC's AM program on Thursday.

"The relationship between the United States and Iran is a matter for them.

"What we are looking to do is to ensure that all parties embrace peaceful and stable principles to ensure that our region is safe."

Defence Industry Minister Christopher Pyne, when asked whether Mr Trump's threats against Iran should be believed, said: "Certainly President Trump has indicated that he's a person who's prepared to act in a way that previous presidents haven't.

"And for that reason, one should always take anything that he says extremely seriously."

US Secretary of Defence James Mattis reinforced America's hard line on Iran while speaking alongside Ms Bishop, Defence Minister Marise Payne and US Secretary of State Michael Pompeo at the AUSMIN meeting in San Francisco mid-week.

Mr Mattis said Iran had been a destabilising influence throughout the region.

"The only reason that the murderer Assad is still in power [in Syria] — the primary reason — is because Iran has stuck by him, reinforced him, funded him," he said.

"We see the same kind of malfeasance down in Yemen, where they're fomenting more violence down there. We've seen their disruptive capabilities demonstrated from Bahrain to the kingdom.

"It cannot continue to show irresponsibility as some revolutionary organisation that is intent on exporting terrorism, exporting disruption across the region. So I think the President was making very clear that they're on the wrong track."

The ABC understands AUSMIN discussed Iran, largely in the context of increasing sanctions on Tehran.

"We're concerned about its ballistic missile program and we talked about ways of constructively engaging with Iran to prevent the development of that program," Ms Bishop told AM.

"But more specifically, we talked about urging Iran to not support proxy groups, whether it's in Syria, Yemen or elsewhere."

Mr Trump withdrew the US from the Iran nuclear deal in May and now seeks complete, verifiable and total denuclearisation, rather than the roll-back and temporary freeze of Iran's nuclear program.

The US plans on reinstating sanctions lifted by the Iran deal by November 4. This includes trade and investment by US firms with Iran and sanctions on Iranian oil exports.

This article was originally published by "ABC" -