Senator Di Natale believes the mission is a dangerous mistake that will ramp up tensions in the Middle East.

Australia will soon send troops, a surveillance plane and a Navy frigate to help guard oil tankers from attacks by Iran.

"We don't spill Australian blood on the back of a request from a dangerous administration, led by a dangerous president," Senator Di Natale told ABC radio on Thursday.

He believes diplomacy is the best solution for the conflict.

"Instead what we're going to do is follow the same mistakes that were made so recently in Iraq - following an administration on the basis of a confected lie into a conflict that led to the death of millions of people."

The prime minister on Wednesday confirmed Australia would join the military mission for an initial six months, which could be extended.

The United Kingdom and Bahrain will also join the US-led effort.

Senator Di Natale said the decision should have been subject to a parliamentary debate and vote.

Deputy Prime Minister Michael McCormack said the Greens and other critics had never regarded Australia's efforts in the Middle East as being of value.

"We need to play our part in the international situation there and we are," Mr McCormack told reporters in Brisbane.

"We've given that support to the US, the UK has too.

"We will continue to monitor the situation. We don't do these things lightly. We do these things in the national interest but we also do these things in the international interest."

Home Affairs Minister Peter Dutton said Australia worked "hand-in-glove" with the US on a range of significant threats.

"It's necessary for the future of our country," he told 2GB radio.

"Nobody can predict what will happen in our region in 10, 20 or 30 years time.

"For us to walk away from the US - as the Greens and others would want us to do - to walk away from that military alliance would be folly, would be dangerous, and would put at risk the stability of our country."

The warship will be redirected from an anti-piracy operation in the Middle East, while the Australian troops will be based in the Bahrain headquarters coordinating the US-led maritime security mission.

Labor supports the decision to send Australian forces to the Strait of Hormuz.

The mission will be a key topic of discussion when Mr Morrison meets the leaders of the seven wealthiest advanced countries in France this weekend.

Australian Associated Press