Mattis made the remarks a day after Australian outlet ABC News published an article, suggesting military action against the Islamic Republic was imminent as early as next month.

According to the report, Australian officials claimed the US was seeking to bomb Iran’s nuclear capability. 

Australian Prime Minister Malcolm Turnbull also denied the report, which cites unnamed Australian officials.

"It's speculation," Turnbull said, according to The Straits Times. "It is citing anonymous sources."

“I have no idea where the Australian news people got that information,” Mattis told reporters. “I’m confident it is not something that's being considered right now, and I think it's a complete — frankly, it's — it’s fiction.”

When asked whether the US had a policy of "regime change or collapse" toward Iran, Mattis said, “There’s none that’s been instituted.”

The report came the same week that President Trump tweeted a threat to Iranian President Hassan Rouhani, telling him to “NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE.”