Malcolm Turnbull and French President Emmanuel Macron say the existing nuclear deal between Iran and six major powers remains the best option available.
Israeli Prime Minister Benjamin Netanyahu this week unveiled what he said was evidence of Tehran's secret efforts in spite of a multilateral deal aimed at limiting its nuclear weapons program.
US President Donald Trump is considering whether to withdraw from a 2015 deal between Iran and six major powers aimed at limiting Iran's nuclear program.
Mr Turnbull told reporters in Sydney after a meeting with Mr Macron that the agreement was the "best option available".
"We support its continuance," the prime minister said.
Mr Macron - whose country negotiated and signed the deal - said it should be respected, however, talks needed to be broadened.
"Whatever the (Trump) decision will be, we will have to prepare such a broader negotiation ... because I think nobody wants a war in the region, and nobody wants an escalation in terms of tension in the region," he said.
