The US secretary of state, Mike Pompeo, has called on other nations to help safeguard tanker traffic in the Persian Gulf following a spate of attacks on ships which Washington blames on Iran.

On a visit to US Central Command headquarters, Pompeo said shipping security in the Gulf was not exclusively a US problem.

“You have China that depends enormously on energy transiting the Strait of Hormuz. You have South Korea, Indonesia, Japan, all of whom have an enormous interest in ensuring there’s freedom of navigation throughout this waterway,” the secretary of state said.

“The United States is prepared to do its part, but every nation that has a deep interest in protecting that shipping lane so that energy can move around the world and support their economies needs to make sure they understand the real threat.”

Pompeo added that “President Trump does not want war, and we will continue to communicate that message, while doing the things that are necessary to protect American interests in the region.”

In an interview on Tuesday, Trump played down the threat to the US represented by the tanker attacks in the region, which he described as being “very minor”.

“Other places get such vast amounts of oil there,” Trump told Time magazine. “We get very little. We have made tremendous progress in the last two and a half years in energy. And when the pipelines get built, we’re now an exporter of energy. So we’re not in the position that we used to be in in the Middle East where … some people would say we were there for the oil.”

The Trump administration is seeking to handle the Gulf crisis amid turmoil in its top ranks. The acting defence secretary, Patrick Shanahan, who Trump had nominated to take on the job official, resigned on Tuesday “to devote more time to his family”, according to a Trump tweet.

Trump named the army secretary, Mark Esper, to take over as acting defence secretary. The US has not had a Senate-confirmed defence secretary in place since December, when James Mattis resigned.

As with his approach to Nato and US Pacific alliances, Trump is focused on persuading allies in the Gulf to shoulder a greater burden in providing security.

The US would be able to rely on Gulf Arab support for tanker protection, but enlisting European involvement is complicated by the fact that European governments see the Trump administration as having precipitating the crisis by walking out of the 2015 multilateral nuclear deal with Iran, and imposing an oil and banking embargo on the country.

On Tuesday, Pompeo confirmed that the visit to Tehran last week by the Japanese prime minister, Shinzo Abe, was made on Trump’s request.

“President Trump had sent … Abe to take a message of his to the leadership in Iran,” the secretary of statem said. Iran’s supreme leader, Ali Khamenei, rejected the proposal of a dialogue with Trump and the two tankers, one of them Japanese-owned, were attacked while Abe was in Tehran.

The deputy chairman of the joint chiefs of staff, General Paul Selva also confirmed on Tuesday that the US had been using Swiss and Iraqi channels as well as public messaging to warn Iran off any direct attack on US interests.

“To engage [the US reinforcements] would be a miscalculation that would lead to a response,” he said. “We don’t want them to do that. We want them to be clear-eyed in whatever it is they are planning.”

He added: “The risks of miscalculation are real.”

Iran has denied responsibility for the blasts that hobbled two tankers in the Gulf of Oman on Thursday, but on Tuesday the commander of the Islamic Revolutionary Guards Corps (IRGC) – which the US says carried out the attack with limpet mines – stepped up the threat to ships travelling through the Strait of Hormuz.

“These missiles can hit with great precision carriers in the sea,” Brig Gen Hossein Salami said in a televised speech. “These missiles are domestically produced and are difficult to intercept and hit with other missiles.”

Anthony Cordesman, a national security analyst at the Centre for Strategic and International Studies, said Arab states in the Gulf could easily help protect tankers with surveillance planes and drones, and could have warplanes at the site of an attack within minutes.

Cordesman acknowledged that deep scepticism over US policy towards Iran has made European governments cautious about being drawn into a conflict, but he argued that the presence of a UK and French naval fleet could offer a powerful political deterrent to further attacks.

“If what you want is a precondition for negotiations, and cool the situation down, there is an incentive for the UK and France to take part – if what you are doing is deterring attacks and monitoring the situation,” Cordesman said.

Nicholas Burns, a former under secretary of state for political affairs, said: “The administration has a credibility problem due to its rash and unwise disavowal of the Iran nuclear deal and its threats to sanction European companies that do business with Iran.”

He added: “But Iran is clearly in the wrong in its activities in the Gulf. The administration is right to consider international convoys. And it is in the clear interest of the European allies, as well as some of the Sunni Arab states, to help the US. At risk is commercial energy traffic in a critical international waterway. Europe, especially, should want to see the free flow of oil and gas for its economic wellbeing.”