The United States wants Australia to impose further economic sanctions on Iran.
But Donald Trump has not asked for a commitment from Australia on joining potential military action against Tehran.
"It certainly wasn't sought ... at this stage I think those issues are a bit premature," Prime Minister Scott Morrison told the ABC on Friday after meeting the US president at the G20 Summit in Japan overnight.
"We would deal with any request from an ally such as the United States seriously and on its merits."
The US is urging Australia to toughen its stance on Iran and play a key role in a new "global coalition" against the regime.
As heightened tensions between the US and Iran threaten to spill into a full-blown conflict, US Secretary of State Mike Pompeo has called on Canberra to partner with the Trump administration to boost pressure on Tehran.
"I think Australia is an important player here," Mr Pompeo told The Australian.
"I think they carry a lot of weight in the sense that they, like many nations, suffer from the fact the world's largest state sponsor of terror continues down the path of building its missile program in a way that threatens not only the Middle East but the entire world."
