Prime Minister Malcolm Turnbull insists it is "not his job" to comment on US President Donald Trump's decision to curb immigration, despite strong criticism from the other international leaders.
More than 110,000 Australian residents were born in one of the seven countries on Mr Trump's temporary immigration blacklist, which bans travel to the US for 90 days.
But thousands more would-be travellers to America may be caught out by another change in US immigration law, which "red flags" Australians who have travelled to Iran, Iraq, Syria or Sudan since March 2011.
Despite these concerns, Mr Turnbull has refused to comment on Mr Trump's executive order, saying instead Australia's immigration and border security policies were "the envy of the world".
"It is not my job as Prime Minister of Australia to run a commentary on the domestic policies of other countries," he said.
"We've got very strong systems — that is a fact. We're proud of those and we'll maintain them and where we can, we will enhance them."
Foreign Minister Julie Bishop has told diplomats in Washington DC to lobby the Donald Trump administration and ensure his latest executive order does not apply to Australian dual nationals.
The Canadian Government claims its citizens are exempt from the new visa restrictions while the UK Government asserts the temporary ban does not apply to full British nationals.
Mr Trump's executive order also suspends all refugee admissions for 120 days with case-by-case exemptions and suspends entry of Syrian refugees indefinitely.
Elsewhere, British Prime Minister Theresa May ordered two of her most senior ministers, Foreign Secretary Boris Johnson and Home Secretary Amber Rudd, to call their US counterparts in protest.
German Chancellor Angela Merkel also spoke out against the ban, saying the fight against terrorism was no excuse for banning refugees.
Canadian Prime Minister Justin Trudeau said his country welcomed those fleeing war and persecution, "regardless of your faith".
Among the first leaders to voice criticism was French President Francois Hollande, who said: "When [Mr Trump] rejects the arrival of refugees, while Europe has done its duty, we should respond to him."
Italian Prime Minister Paolo Gentiloni said "open society, plural identity, no discrimination" were the "pillars of Europe", while the Danish, Swedish and Norwegian Governments also registered their opposition.
Many Australians "red flagged" because of previous travel have since been turned away at airport check-in desks, unaware their travel history is now a barrier for entry.
This has included Australians planning to transit through a US airport to a third country.
Those who were blocked could apply for a traditional non-immigrant visa from the Department of Homeland Security, but needed to do so in advance of their travel.
The Department of Foreign Affairs and Trade has since updated its travel advice for Australians travelling to the US warning of changes in American policy.
"Any of these Australians who have previously been issued an Electronic System for Travel Authorisation [ESTA] are likely to have the ESTA revoked," the statement said.
Opposition Leader Bill Shorten said the temporary ban was "appalling and ought to be ended as soon as possible".
"I urge Malcolm Turnbull to reconsider what our nation’s position ought to be and rethink what he should be saying on our behalf," he said.
Labor's Tanya Plibersek said the Government was "missing in action" and needed to provide Australian travellers with clarity.
"I think it's absolutely vital now that the Australian Government seek clarification about how this will affect Australian citizens," she said.
