A convoy of oil tankers has passed through the Strait of Hormuz, vessel tracking data shows, after Iran declared the waterway 'completely open'.
But Tehran warned it could shut the Strait of Hormuz again if the United States continues its blockade of Iranian ports, raising fresh fears over the vital global trade route.
MarineTraffic data showed several vessels moving through the channel, including tankers carrying oil, liquefied petroleum gas and chemicals.
The potential resumption of transit had lifted stock markets on Friday and prompted optimism in Washington, with President Donald Trump saying a broader US-Iran peace deal was 'very close'.
Trump said Tehran had agreed to hand over its enriched uranium, a key sticking point in negotiations, but Iran pushed back on the claim, insisting its stockpile was not going anywhere.
It also warned that if US warships intercept vessels coming from Iranian ports, the Strait of Hormuz, a key global trade artery through which about a fifth of the world's crude oil and liquefied natural gas passes, could be closed again.
'With the continuation of the blockade, the Strait of Hormuz will not remain open,' parliamentary speaker Mohammad Bagher Ghalibaf wrote on X, adding that passage through the waterway would require authorization from Iran.
Tracking site MarineTraffic shows several ships appearing to be moving through the waterway
President Donald Trump waves to reporters as he walks on the South Lawn upon his arrival to the White House, Friday, April 17
Pictured: U.S. Navy guided-missile destroyers executing a blockade mission impacting Iranian ports
'What they call a naval blockade will definitely be met with an appropriate response from Iran,' said Iranian foreign ministry spokesman Esmaeil Baqaei, calling the naval blockade 'a violation of the ceasefire' it struck with Washington for a fortnight to enable talks.
US forces have so far directed 21 ships to turn around since the blockade began this week, the US Central Command posted on X overnight, accompanied by an image of an American guided-missile destroyer patrolling the Arabian Sea.
Trump also mocked Western allies over plans to deploy a British and French-led naval taskforce to patrol the Strait of Hormuz.
Sir Keir Starmer and Emmanuel Macron said on Friday they would send warships to help secure the key shipping route, which carries roughly a fifth of the world's oil.
But the US president dismissed the effort in a post on X, writing: 'I told them to stay away… They were useless when needed, a paper tiger.'
The sour notes came on a day that Trump had hailed as 'GREAT AND BRILLIANT,' with a series of social media posts praising talks mediator Pakistan and Gulf allies.
Despite the discord over the status of the strategic waterway, Pakistani leaders whose mediation led to historic face-to-face talks between Washington and Tehran envoys in Islamabad last week, pushed for the warring sides to finalize an agreement to end the war.
In his phone interview with AFP, Trump added: 'Looks like it's going to be very good for everybody. And we're very close to having a deal,' adding that there were 'no sticking points at all' left with Tehran.
That echoed the US president's earlier comments he would consider flying to Pakistan to sign any deal struck, raising hopes of another meeting in Islamabad after US Vice President JD Vance left last weekend after 21 hours of talks he said ultimately could not strike a permanent deal.
But casting a shadow of doubt, Trump reiterated on Saturday that he planned to maintain the US naval blockade if a peace deal with Iran were not reached, though he signalled he was open to extending the ceasefire with Iran after it expires on Wednesday.
'Maybe I won't extend it, but the blockade is going to remain,' Trump told reporters aboard Air Force One.
Oil prices had already fallen on hopes of a negotiated end to the conflict, and the drop accelerated on Friday, with stocks heading upwards as traders soaked up the optimism.
This US Navy handout photo released by US Central Command public affairs shows the Arleigh Burke-class guided-missile destroyer USS Thomas Hudner (DDG 116) firing a Tomahawk land attack missile in support of Operation Epic Fury on March 1
Late Friday, the US issued another waiver allowing the sale of Russian oil and petroleum products already at sea, a move likely to further soften oil prices by boosting supply on global markets.
The start of a 10-day ceasefire in Lebanon on Friday and the reopening of the strait marked progress in Washington's push for a broader deal to end its war with Iran, after Tehran insisted that halting the fighting between Israeli forces and Iran-backed Lebanese group Hezbollah must be part of any larger agreement to end the regional conflict.
In Lebanon, displaced families began returning to their homes in bomb-damaged south Beirut and the country's war-ravaged southern towns.
'Our feelings are indescribable, pride and victory,' 37-year-old Amani Atrash told AFP, adding that she hoped the ceasefire would be extended.
The fighting in Lebanon began on March 2, when Hezbollah fired rockets at Israel days after the wider Middle East war began and in retaliation for the killing of Iran's supreme leader Ali Khamenei.
Trump said Israel had been 'prohibited' by Washington from carrying out further strikes and that the United States would work with Lebanon 'and deal with the Hezbollah situation in an appropriate manner.'
Prime Minister Benjamin Netanyahu warned that the campaign against Hezbollah was not over.
'We have not yet finished the job,' he said, adding that a key objective was the 'dismantling of Hezbollah'.
Hezbollah, meanwhile, warned it remained ready to respond to any Israeli violations.
