The US secretary of state, Mike Pompeo, has said Washington and its allies were seeking a “peaceful resolution” with Iran in the wake of the attack on Saudi oil facilities, making clear that Washington would limit its initial response to further sanctions.

Pompeo’s remarks, made on his return trip to Washington after visits to Saudi Arabia and the United Arab Emirates, mark a significant cooling of rhetoric after Donald Trump had warned the US was “locked and loaded” and Pompeo had said the attack, which he blamed on Iran, was “an act of war”.

The Pentagon said its goal was “to deter conflict and get back on the diplomatic path” and stopped short of definitively blaming Tehran for the air strikes which knocked out half Saudi Arabia’s oil production, deferring to Riyadh to make that assessment.

“As of this time all indications are that Iran is in some way responsible,” spokesman Jonathan Hoffman said, before adding: “We’re not going to get ahead of the Saudi investigation in their assessment of this.”

Iran has insisted the attack on a Saudi oil field and refinery was launched from Yemen by Houthi rebels, who have claimed responsibility. Any reprisal attack on Iran by the US or Saudi Arabia, Iranian foreign minister Mohammad Javad Zarif warned, would lead to “all-out war”.

“I make a very serious statement about defending our country. I am making a very serious statement that we don’t want to engage in a military confrontation,” Zarif told CNN. “But we won’t blink to defend our territory.”

Asked about Zarif’s comments, Pompeo sought to defuse the stand-off.

“I was here in an act of diplomacy. While the foreign minister of Iran is threatening all-out war and to fight to the last American, we’re here to build out a coalition aimed at achieving peace and a peaceful resolution to this,” the secretary of state said. “That’s my mission set, what President Trump certainly wants me to work to achieve, and I hope that the Islamic Republic of Iran sees it the same way. There’s no evidence of that from his statement, but I hope that that’s the case.”

Multiple reports from the White House have portrayed Trump as extremely reluctant to be drawn into another conflict as he campaigns for reelection while seeking to draw down troop levels in Afghanistan and Syria.

Pompeo repeated Trump’s warning that Washington would impose further sanctions on Iran, which is already subject to a US oil and banking embargo, arguing that they were effective in cutting Iranian financing for its regional allies and its missile programme.

“The president’s direction to us, to continue to prevent them having the capacity to underwrite Hizbullah, Shia militias in Iraq, their own missile program, all the things that they have done to pose a threat to the world, that’s the mission set with our economic sanctions,” he said.

Pompeo was speaking after consulting Saudi crown prince Mohammed bin Salman and UAE prince Mohammed bin Zayed, the Trump administration’s closest allies in the region, particularly in the wake of Israeli elections that threw Binyamin Netanyahu’s political future in question.

Trump had made clear that Saudi Arabia would have to take the lead role in any response for Saturday’s attacks. But Saudi officials have made it clear they did not want to trigger a full-scale conflict.

The Pentagon said the focus of its own response was to explore “potential ways to look at mitigating future attacks”.

Trump’s decision not to retaliate against Iran drew criticism from Republican hawks like the South Carolina senator Lindsey Graham, who said that US inaction “was clearly seen by the Iranian regime as a sign of weakness”.

Most Trump critics applauded US restraint, claiming that the US had under no obligation to Riyadh, but blamed Trump’s rhetorical bluster and his policy of “maximum pressure” on Iran for driving the region to the brink of conflict.

“US inaction will be perceived as weakness,” said Suzanne Maloney, deputy director of the foreign policy programme at the Brookings Institution. “Let me be clear: I’m not advocating war. The point is that [Trump] engaged in a stupid, unnecessary, incredibly dangerous bluff and the Iranians have called him on it.”