"To allow diplomacy to run its course, I earnestly request President Trump to extend the deadline for two weeks. Pakistan, in all sincerity, requests the Iranian brothers to open Strait of Hormuz for a corresponding period of two weeks as a goodwill gesture," Sharif said in a post on X.
Trump has given Iran until 8pm in Washington DC on Tuesday (10am on Wednesday AEST) - 3.30am in Tehran - to end its blockade of Gulf oil or face US forces destroying every bridge and power plant in Iran.
Sharif urged "all warring parties" to observe a ceasefire everywhere for two weeks "to allow diplomacy to achieve conclusive termination of war".
He added that diplomatic efforts to settle the war peacefully were "progressing steadily, strongly and powerfully with the potential to lead to substantive results in near future".
Trump is aware of Pakistan's proposal for a two-week extension and a response will come soon, Axios reported on Tuesday, citing White House press secretary Karoline Leavitt.
Iran was positively reviewing Pakistan's request for a two-week ceasefire, a senior Iranian official told Reuters on Tuesday.
Sources told Reuters earlier on Tuesday that talks between the United States and Iran were at risk of being derailed following Iranian attacks on Saudi Arabian industrial facilities.
If Saudi Arabia were to retaliate, the talks would be over, a source said, adding that could draw Pakistan into the conflict under its defence pact with Saudi Arabia which binds both countries to fight for each other in case of a war.
Pakistan has been the main go-between for proposals shared by Iran and the United States but there has been no sign of a compromise.
Trump threatened that "a whole civilisation will die tonight" if Iran did not open the Strait of Hormuz.
Iranian authorities said they would retaliate against US allies in the Gulf, whose desert cities would be uninhabitable without power or water.
As the clock ticked down on Trump's deadline, strikes on Iran intensified, hitting railway and road bridges, an airport and a petrochemical plant.
US forces attacked targets on Kharg Island, home to Iran's main oil export terminal.
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