Iran was “unmistakably" responsible for attacks on two tankers in the Gulf of Oman last week but the US is not looking for a war with Tehran, Secretary of State Mike Pompeo said on Sunday.
"President Trump has done everything he can to avoid war. We don't want war," Mr Pompeo told Fox News Sunday.
But he said that Washington would guarantee free navigation through vital shipping areas.
"The United States is going to make sure that we take all the actions necessary, diplomatic and otherwise that achieve that outcome," Mr Pompeo said.
On Thursday, Japanese and Norwegian tankers were attacked in the Gulf of Oman, which lies near crucial Strait of Hormuz, leaving them ablaze.
It followed attacks on four tankers – two Saudi, one Norwegian and one Emirati – off the coast of Fujairah, in the UAE, on May 12.
An investigation by the three countries blamed those attacks on a state actor. The US has held Iran responsible for both sets of attacks.
In a show of unity, the Saudi Arabian Air Force flew in formation with US fighter jets over the Gulf, Saudi state news agency Spa reported on Sunday.
Japan's Kokuka Courageous, which was carrying a large shipment of methanol, and Norway's Front Altair are being assessed off the UAE's coast before their cargoes are unloaded.
"Kokuka Courageous has arrived safely at the designated anchorage at Sharjah," the vessel's BSM Ship Management, based in Singapore, said Sunday.
The Front Altair was being towed towards an area off the coast of Fujairah.
The Norwegian vessel’s owners said all crew members were in Dubai, where they would "assist with the debrief to the owner's legal team and the appropriate authorities before returning home".
Both vessels were heading for Asia when they were attacked about 18 kilometres apart.
The US released footage that it said showed members of the Islamic Revolutionary Guard Corps removing an unexploded limpet mine from the hull of the Japanese tanker.
The attack came on the same day Japanese Prime Minister Shinzo Abe was paying a rare visit to Iran.
Iran has previously threatened to block the Strait of Hormuz in protest against US policies, in a move that would severely disrupt the movement of oil supplies around the world.
The attacks sent crude prices soaring and the UAE and Saudi Arabia called on the international community to secure access to oil supplies.
Mr Pompeo, who led the CIA before becoming secretary of state, promised to provide further evidence of Iran's role in the attacks.
"The intelligence community has lots of data, lots of evidence," he said. "The world will come to see much of it."
Mr Pompeo said he did not want to discuss next steps the US might take in response to last week's developments.
"Iran will not get a nuclear weapon. That's the goal," he said.
He was referring to the possibility of the US sending more American troops and military hardware to the region.
It has already sent an aircraft carrier strike force and B-52 bombers to the region to defend US interests.
"I made a number of calls to colleagues around the world yesterday," Mr Pompeo said. "I am confident that we will have partners that understand this threat."
The attacks have taken place during a sensitive period when the nuclear deal signed between Tehran and world powers in 2015 is hanging in the balance.
US President Donald Trump pulled America out of the deal in May 2018, and Iran watered down its commitments to the deal on the anniversary of his withdrawal.
Other signatories of the deal have blamed Iran for the tanker attacks.
British Foreign minister Jeremy Hunt said on Sunday Britain was "almost certain" Iran was behind attacks and that London did not believe anyone else could have done it.
London’s ambassador to the Iran denied on Sunday that he was summoned by the Iranian Foreign Ministry.
"Interesting. And news to me," Rob Macaire said on Twitter a day after the Iranian Foreign Ministry said it had summoned him over his government's accusations.
The ministry said the head of its European affairs division, Mahmoud Barimani, met Mr Macaire on Saturday and "strongly protested against the unacceptable and anti-Iranian positions of the British government".
Britain is to send 100 elite Royal Marines to the Gulf to protect naval ships after the attacks.
The soldiers are a rapid reaction force operating from ships patrolling the region from a new base in Bahrain, The Sunday Times reported.
Iran’s proxy in Yemen, the Houthi rebels, have increased their attacks against Saudi Arabia in recent weeks.
Tehran has been arming the group with missiles and drones that it launches at the kingdom.
Saudi Arabia intercepted five drones on Friday. Two days earlier, a rebel missile hit the Saudi airport of Abha, wounding 26 civilians.
Another drone was intercepted on Saturday but it caused no damage.