Qatar has rushed a team of mediators to Tehran in a sign that talks to open the strait of Hormuz, in return for the lifting of US sanctions and asset freezes, are reaching a climax.

The aim would be to sign a memorandum of understanding on the strait that would lead to 30 days of talks on Iran’s nuclear programme – so deferring discussion of the US demand that Iran hand over its stockpile of highly enriched uranium.

Until now, Qatar, often seen as the most skilled mediator in the Middle East, has not been directly acting as a go-between in the US-Iran conflict, leaving the task initially to Oman and more recently to Pakistan.

The head of the Pakistan army, Field Marshal Asim Munir, was also expected in Tehran, but Iran was playing down reports of a breakthrough.

The US secretary of state, Marco Rubio, said that while there had been “a little progress”, the US would not accept Iran being given a power to impose tolls on commercial shipping through the strait of Hormuz. He said Pakistan remained the main interlocutor for the US.

The latest diplomatic moves came amid US media reports that the US is weighing new military strikes on Iran, although both Axios and CBS said that a final decision had not been been made.

The reports emerged hours after Trump said he would not travel to attend his son’s wedding this weekend due to “circumstances pertaining to government” and his “love for the United States of America.”

Iran has set up a Persian Gulf Strait Authority (PGSA) that would impose tolls, as well as direct shipping on to specific waterways, but the US insists tolls cannot be an option.

Anwar Gargash, a senior diplomatic adviser to the United Arab Emirates, warned Iran might be over-negotiating, saying they “have a tendency to overestimate their cards”.

Pakistan’s interior minister, Mohsen Naqvi, met the Iranian foreign minister, Abbas Araghchi, for the second time in two days on Friday morning.

It is thought Pakistan might try to bring in China as a guarantor of any deal. Pakistan’s prime minister, Shehbaz Sharif, is due in Beijing on Saturday.

Iran has emphasised that it is seeking to postpone all talks on its nuclear programme and focus instead on a permanent cessation of hostilities, which it hopes will include a phased lifting of US sanctions, the unfreezing of frozen Iranian assets, compensation for US-Israeli war damage, and commitments not to resort to force in future.

The future management of the strait of Hormuz is a key point of dispute, with Pakistan floating plans for joint control under UN auspices.

Five Gulf states have written a letter to the International Maritime Authority, a global shipping watchdog, urging merchant and commercial ships not to engage with the PGSA.

Thesignatories are Bahrain, Kuwait, Qatar, Saudi Arabia and the UAE. The list does not include Oman, but Oman, which under the proposal would be the authority on the south side of the strait, is wary of Tehran’s proposal.

In their letter, the five states warn: “Iran’s purported route should be seen for what it is, an attempt to control traffic through the strait by forcing vessels to use a route within its territorial waters, which can be exploited for monetary gain through the imposition of toll fees.

“Any understanding or recognition of Iran’s proposed route and PGSA as an alternative would set a dangerous precedent.”

At a Nato foreign ministers meeting in Sweden, Rubio said: “Iran is trying to create a tolling system. They’re trying to convince Oman … to join them in a tolling system in an international waterway. There is not a country in the world that should accept that.”

He again expressed his disappointment at Europe’s refusal to do more to keep the strait open.

Meanwhile, analysts argue that much of what US administration officials say about the status of the talks has to be filtered through Washington’s need to massage the global price of oil down.

Esmail Baghaei, spokesperson for the Iranian ministry of foreign affairs, told state media: “At this stage, the focus of the negotiations is on ending the war on all fronts, including Lebanon, and the claims made in the media about nuclear issues, including the issue of enriched material or the enrichment debate, are merely media speculation and lack credibility.”

Baghaei was referring to speculation that has arisen after Trump’s statements on Thursday when he spoke about Iran’s stockpile of highly enriched uranium.

He said: “We will get it. We don’t need it, we don’t want it. We will probably even destroy it after we get it, but we will not let them get it.”

Russia has offered to receive the stockpile, but Iran says it will downblend the stockpile inside Iran itself.