Donald Trump has said he cancelled planned military strikes against Iran on the basis of “rapidly” reaching a deal on its nuclear programme and the full opening of the strait of Hormuz.

The US president paused the strikes in expectation of a breakthrough and in response to requests from Iran and other countries in the region, he claimed on his Truth Social platform on Saturday.

“Based on this request, I have agreed, for the future benefit of the WORLD and, likewise, the survival of a successful and prosperous Iran, to cancel the attack, subject to being able to rapidly make a DEAL.”

The deal would include the immediate and complete reopening of the strait and “an end to Iran’s nuclear threat”, he posted. It marked the latest climbdown from extravagant threats to pound the Islamic Republic in the months-long conflict.

However, hopes of a breakthrough faded on Sunday when Iran’s Mehr news agency said Trump’s claim that Tehran had requested a pause “was nothing but a new lie” and that the Iranian armed forces were “on high alert and ready for any eventuality”.

Another Iranian news agency, Fars, citing a source close to Iranian negotiators, said that as long as the US “maintains its hostile actions” the strait will remain closed.

The decision to halt fresh strikes came after the Saudi crown prince Mohammed bin Salman called Trump on Saturday to express concerns , it was reported. Trump’s reversal also followed Iranian threats to retaliate decisively against its neighbours in the event of US strikes, while Kuwait reported being hit by Iranian drones on Saturday and two ships were attacked off Oman in the strait of Hormuz.

One source described as having knowledge of the Trump-Mohammed call told Axios that the Saudi crown prince had “urged Trump to de-escalate and refrain from launching the strikes”.

The Associated Press also reported the conversation, citing its own source. It said the Saudis were concerned that if the US targets Iran’s energy infrastructure or carries out massive strikes on other key infrastructure, Tehran could respond by carrying out similar attacks on the kingdom and other Gulf countries.

The crown prince during Saturday’s call sought clarity from Trump on what potential new action he was weighing to take against Iran, the Associated Press reported.

A White House official, who was not authorised to comment publicly and requested anonymity, confirmed to the Associated Press that Trump and Prince Mohammed spoke on Saturday but did not offer any detail about the substance of their conversation.

Saudi Arabia earlier this week joined the US in striking logistics and weapons sites used by Iranian-backed militias in Iraq, but has been urging the US and Iran to get back to the negotiating table.

CBS News reported that the US and Israel were planning joint strikes, possibly throughout the weekend, with oil refineries and power plants among possible targets.

Iran warned this weekend against any “adventurous action” by the US and said it ⁠would retaliate decisively. Tehran foreign minister Abbas Araqchi’s comments in separate phone calls on Saturday with senior Turkish, Pakistani and Saudi officials came just hours after Kuwait’s army said it destroyed hostile ⁠drones launched by Iran against several vital facilities.

A government facility in northern Kuwait and civilian property belonging to a company ​on Bubiyan Island were hit, with falling ​shrapnel causing material damage but no casualties, the Kuwaiti ​army said.

The United Kingdom Maritime Trade Operations said on Saturday it had received reports of two maritime incidents off Oman, including one in which a tanker was struck by an unknown projectile that damaged the engine room. In the other incident, the master of a tanker reported seeing a large splash and an explosion close to the vessel, though no damage was reported.

Iran’s Araqchi told regional counterparts that any attacks by the US and ​Israel or participation by regional countries in such actions would be ‌met with a “proportionate response”. Nournews, a ‌media outlet affiliated with Iran’s top security body, said on Saturday that US attacks on Iranian energy infrastructure would prompt Iranian strikes on oilfields in Saudi Arabia and the United Arab Emirates, as well as the gasfields of Qatar and Israel.

The developments appeared to have given Trump pause for thought, as he posted on Saturday night in characteristically grandiose language that “the USA is locked and loaded” to strike Iran with “military terror, strength, and power not seen since World War II”.

Reuters, Agence France-Presse and Associated Press contributed to this report