Pakistani Prime Minister Shehbaz Sharif on Tuesday asked President Donald Trump for a two-week extension of his threat to wipe out the "whole civilization" of Iran unless Tehran strikes a deal that includes reopening the Strait of Hormuz.

Sharif in an X post also asked Iran's leadership to agree to open up the strait for two weeks "as a goodwill gesture."

"We also urge all warring parties to observe a ceasefire everywhere for two weeks to allow diplomacy to achieve conclusive termination of war, in the interest of long-term peace and stability in the region," Sharif wrote.

The public plea from the leader of Pakistan, which has acted as a mediator between the warring powers, came hours before Trump's 8 p.m. ET deadline for Iran to either cut a deal or face massive strikes on its civilian infrastructure — which could be considered a war crime.

On Tuesday morning, Trump dramatically ramped up his threats, warning on Truth Social that "a whole civilization will die tonight, never to be brought back again" if no agreement is reached.

"However, now that we have Complete and Total Regime Change, where different, smarter, and less radicalized minds prevail, maybe something revolutionarily wonderful can happen, WHO KNOWS?" he wrote.

"We will find out tonight, one of the most important moments in the long and complex history of the World."

Asked for comment on Sharif's request, White House press secretary Karoline Leavitt told CNBC, "The President has been made aware of the proposal, and a response will come."

Trump's threat came after U.S. forces the previous night struck military targets on Kharg Island, Iran's main oil export terminal, a White House official confirmed to CNBC.

Iran has blocked most oil transit through the Strait of Hormuz since the U.S. and Israel began the war in late February. The closure has led to a historic oil supply shock, which quickly sent global energy prices soaring.

Trump has boasted that Iran's military has been "obliterated" but acknowledged it still controls ship traffic flow through the strait, giving it key leverage.

In a belligerent Easter social media post on Sunday, he threatened to destroy Iran's bridges and power plants by Tuesday night, demanding Tehran "Open the Fuckin' Strait, you crazy bastards, or you'll be living in Hell."

Tuesday's post, and the reports of new U.S. and Israeli strikes on Iranian infrastructure, gave way to conflicting reports on the status of diplomatic efforts between the warring powers.

But Sharif wrote in his X post, "Diplomatic efforts for peaceful settlement of the ongoing war in the Middle East are progressing steadily, strongly and powerfully with the potential to lead to substantive results in near future."

The PM's post tagged the official social media profiles of top officials including Trump, Vice President JD Vance, Secretary of State Marco Rubio and U.S. Special Envoy Steve Witkoff, as well as Iran's president, foreign minister and parliamentary speaker.

Trump's latest threat quickly drew heated reactions from his political opponents plus some who have long been aligned with his MAGA political movement.

"Congress must immediately end this reckless war of choice in Iran before Donald Trump plunges us into World War III," House Minority Leader Hakeem Jeffries, D-N.Y., said on X. "It's time for every single Republican to put patriotic duty over party and stop the madness."

Republican former Rep. Marjorie Taylor Greene, a onetime Trump loyalist who left Congress in January after publicly falling out with the president, called for his removal from office via the 25th Amendment.

Many Democratic lawmakers have since joined that call.

Pope Leo XIV also weighed in Tuesday outside the papal residence in Castel Gandolfo, urging people of good will to "reject war, especially a war which many people have said is an unjust war, which is continuing to escalate and which is not resolving anything."

Great Britain, meanwhile, is not allowing the U.S. to use its bases as part of any operations targeting civilian infrastructure, U.K. news outlet The i Paper reported.

A spokesperson for the British Ministry of Defence told CNBC it has authorized the U.S. to use its bases for "specific defensive operations to prevent Iran firing missiles into the region, which is putting British lives at risk."

"We won't be providing a running commentary on our allies' operations, including their use of our bases," the spokesperson added.

Trump has frequently fumed about the reluctance of the U.K. and other allies in the North Atlantic Treaty Organization to involve themselves in the Iran war, even as he claims the U.S. does not need any help.

The relationship between the U.S. and the alliance was deeply strained earlier this year, when Trump demanded that the U.S. must take control of Greenland, an autonomous territory ruled by NATO member Denmark.

Trump's saber-rattling toward Greenland subsided, but he signaled Monday that he remains upset with NATO over Europe's opposition to his efforts to seize the island.

"You know, it all began with, you want to know the truth, Greenland," Trump said at the end of a White House news conference on Monday. "We want Greenland. They don't want to give it to us. And I said, 'Bye, bye.'"

At that news conference, Trump said that for Iran to stave off the Tuesday deadline, it would have to agree to "a deal that's acceptable to me, and part of that deal is going to be, we want free traffic of oil and everything else."

Trump has criticized Iran's talk of tolling the strait and has signaled his interest in the U.S. imposing its own tolls there instead.

The U.S., Iran and regional mediators in the Middle East were reportedly discussing a 45-day ceasefire proposal as a last-ditch attempt to avoid triggering Trump's looming deadline.

But a White House official told CNBC on Monday morning that Trump has not backed that idea, and Iran has explicitly rejected any temporary ceasefire, calling instead for a deal to end the war permanently.

"The only one that's going to set a ceasefire is me," Trump told reporters at the White House Easter Egg Roll on Monday when asked about the proposal.

Trump has insisted the Iranian people want the U.S. to keep up its military operations even if it puts them at risk, because they have lived in a "violent, horrible world" under the repressive ruling regime.

"They would be willing to suffer that in order to have freedom," he said at Monday's news conference. "We've had numerous intercepts, 'Please keep bombing.' Bombs that are dropping near their homes. 'Please keep bombing. Do it.'"

But Trump has also argued that Iran's new regime, which replaced the many top officials killed by the U.S. and Israel during the war, is more reasonable and less radical.

Not everyone agrees. JPMorgan research analysts said in a Monday client note that the conflict has empowered the Revolutionary Guard and that Iran's strategy is based around its ability to outlast, rather than outgun, its opponents.

"Iran may have lost its supreme leader and commanders, and suffered severe damage to nuclear facilities and military assets, but there are no signs of capitulation," they wrote.

— CNBC's Jackson Peck contributed to this report.