Washington's looming tariffs on steel and aluminium are "entirely unjustified", Australian Prime Minister Anthony Albanese said on Wednesday after failing to secure a last-minute exemption.

"This is not a friendly act," Albanese told reporters, after the White House dashed hopes that Australia would be excluded from blanket 25 percent levies on steel and aluminium.

"Quite clearly it is not a positive step in our relationship. It is as simple as that."

US President Donald Trump's decision to slug close ally Australia was "entirely unjustified", Albanese said.

"This is against the spirit of our two nations' enduring friendship. Friends need to act in a way that reinforces, to our respective populations, the fact that we are friends."

Despite the setback, Albanese said Australia would not retaliate.

"Tariffs and escalating trade tensions are a form of economic self-harm and a recipe for slower growth and higher inflation", he added.

Albanese hinted that Australia may be one of the few nations to secure an exemption following a phone call with Trump in February.

White House officials told Australian media overnight that the exemption was no longer on the table.

"He considered it, and considered against it," spokeswoman Karoline Leavitt told national broadcaster ABC.

Australia is a minor global player in steel export markets but is a dominant source of iron ore, a key raw ingredient in the alloy.

Australian steel producer BlueScope said it employed around 4,000 staff in the United States. (AFP)