Iran has said it will keep the Strait of Hormuz closed until the United States fulfils commitments Tehran says were made under an interim agreement, setting out demands including an end to the US blockade and oil sanctions.

Mohammad Baqer Qalibaf, Iran's parliament speaker and a senior negotiator, told parliament on Tuesday that Washington must lift its blockade of Iranian ports, remove oil sanctions, release frozen Iranian assets and end military threats and operations before the strategic waterway is reopened.

"Until the United States fulfills its commitments under the agreement ... the Strait of Hormuz will not reopen," Qalibaf said, according to the Associated Press.

His statement directly contradicted US President Donald Trump, who said on Tuesday that the strait was "open and operating" and that Washington's naval blockade remained in force.

"There are no talks or conversations going on, or scheduled, with the Islamic Republic of Iran," Trump wrote on Truth Social, adding that all water mines in the strait had been removed or detonated.

The competing claims followed the expiry of a 60-day period for Washington and Tehran to negotiate a broader settlement under a memorandum of understanding signed on 17 June.

The agreement called for an end to military operations and set a timetable for negotiations covering wider disputes, including Iran's nuclear programme. It quickly began to unravel over control of the Strait of Hormuz. Trump declared the agreement "over" on 7 July, and Iran's foreign ministry announced its suspension a week later.

A senior Iranian official told Reuters on Monday that Tehran would now adopt a "fully offensive" military posture because efforts to secure a permanent end to the war had stalled. The official said Iran could carry out a "timely and precise" attack intended to break the US naval blockade if diplomacy failed.

The dispute has left commercial shipping through Hormuz severely restricted. Before the war, roughly one-fifth of global oil and liquefied natural gas supplies passed through the narrow waterway between Iran and Oman.

Five commodity vessels crossed the strait on Saturday and none were recorded on Sunday, according to Kpler ship-tracking data cited by Reuters, compared with 31 during the previous weekend.

The maritime risk was underlined again on Tuesday when the United Kingdom Maritime Trade Operations agency said a vessel leaving the strait was struck by an unidentified projectile off Oman.

The impact damaged the vessel's engine room and resulted in what UKMTO described as a "crew casualty". The agency did not initially say whether the crew member had been killed or wounded. Oman's coastguard was assisting the remaining crew and authorities were investigating, according to the Associated Press. No party immediately claimed responsibility.

Diplomatic messages from Washington have also appeared contradictory. Jared Kushner, Trump's special envoy and son-in-law, said on Monday that contacts between the US government and different parts of the Iranian government were more extensive than they had previously been.

Trump said a day later that no talks were taking place or scheduled.

Turkish President Recep Tayyip Erdoğan urged Trump during a telephone call to pursue negotiations with Iran, according to the Turkish presidency. Ankara also offered to support efforts to reduce tensions and reach a settlement.

Oil markets have reacted to the prospect of a prolonged disruption. Brent crude settled at $90.87 a barrel on Monday, up $2.35, while US West Texas Intermediate rose $2.10 to $84.50.

Iran has separately been negotiating with Oman over arrangements for managing shipping through Hormuz. Tehran said on Monday that the details of a joint statement were being finalised, but no agreement reopening the waterway had been announced by Tuesday.