AFP -US Defense Secretary Jim Mattis said Friday he does not see the need for a stepped-up military posture against Iran, the day after a top diplomat said evidence shows Tehran is supporting Huthi rebels in Yemen.

US ambassador to the United Nations Nikki Haley on Thursday presented missile fragments and other military gear that she said came from Iran and had been used against US ally Saudi Arabia.

When asked if he thought such evidence warranted an emboldened or expanded military response from the US, Mattis said: "Not militarily, no."

"It's the reason Ambassador Haley was there and not one of our generals," he told Pentagon reporters.

"This is a diplomatically-led effort to expose to the world what Iran is up to."

"To expose what they are doing is healthy for the international community for their awareness of what's going on there."

Haley on Wednesday said a missile fired on November 4 from Yemen toward Riyadh airport had been made in Iran.