WASHINGTON (Reuters) - U.S. Defense Secretary Jim Mattis moved to allay concerns on Wednesday that the United States had alienated itself from close allies with its decision to withdraw from an international nuclear deal with Iran.

Mattis, who once spoke publicly of the need to abide by the Iran nuclear deal but later tempered that position, did not suggest any split with President Donald Trump in the wake of Trump’s his decision to pull out of the Iran nuclear deal.

But, a day after Trump roiled ties with European allies by publicly withdrawing from the deal, Mattis suggested he was still working with U.S. partners to address Washington’s concerns about Iran’s nuclear ambitions and regional actions.

“We will continue to work alongside our allies and partners to ensure that Iran can never acquire a nuclear weapon, and will work with others to address the range of Iran’s malign influence,” Mattis told a hearing before the U.S. Senate Appropriations Committee.

Dismayed European allies sought to salvage the international nuclear pact and preserve their business with Iran. Since taking the Pentagon’s top job last year, Mattis has strengthened ties with European allies - even as Trump has raised questions about the trans-Atlantic NATO alliance.

Trump said Iran would now either negotiate or “something will happen.” It was not immediately clear what actions he was suggesting would take place.

Trump’s decision raised the risk of deepening conflicts in the Middle East and cast uncertainty over global oil supplies. Oil prices rose more than 3 percent on Wednesday, with the Brent crude futures benchmark touching a 3-1/2-year high.

Mattis did not suggest military action was in the offing, telling the Senate committee that holds the U.S. government’s purse strings that he did not anticipate asking for more funds for the U.S. military because of the Iran deal.

That is, unless Iran were to act first.

“I do not anticipate asking for more dollars. Should Iran do something, that is a different issue. But no, I am not coming to you with an additional supplemental funding request,” Mattis said.

The U.S. pullout could strengthen the hand of hard-liners in Iranian politics at the expense of moderates like President Hassan Rouhani, who had pinned their hopes on the deal to boost living standards in Iran, with limited success so far.

In private conversations, Mattis stressed the need to act with allies, given the threat he believes that Iran poses in the region, one U.S. official familiar with the conversations told Reuters. But he also publicly acknowledged the Iran nuclear agreement was imperfect and needed to be fixed.

In Wednesday’s hearing, Mattis said Trump’s decision to withdraw from the deal had not been hasty.

“The president could not affirm as required that this agreement was being lived up to,” Mattis said.

“I think we now have the opportunity to move forward to address those shortcomings and make it more compelling.”