"The Deal with the Islamic Republic of Iran is now complete," US President Donald Trump wrote on his Truth Social platform shortly after Pakistani Prime Minister Sharif made the announcement.
The agreement was struck despite an Israeli strike on Lebanon on Sunday that drew criticism from both Iran and Trump.
The precise terms of the deal were not immediately known.
Sharif said the pact called for "the immediate and permanent termination of military operations on all fronts, including in Lebanon".
Multiple sources previously told Reuters that the draft deal would reopen the Strait of Hormuz, end the US blockade of Iranian ports and extend a ceasefire, while leaving Iran's nuclear program to be addressed during a 60-day period of additional talks.
Trump said the strait would be open "toll free" and that the US naval blockade would also end.
"Ships of the World, start your engines. Let the oil flow!" Trump wrote.
Earlier on Sunday, Iranian negotiator Mohammad Baqer Qalibaf said Israel's latest attack on the southern suburbs of Beirut, which Israel said targeted Iranian-backed Hezbollah militants, showed the US lacked "the will and ability to fulfill your commitments", in a post on X.
Iran's foreign ministry said it held the US responsible for the attack. Iran warned of a "strong response", and its top joint military command said the "finger (is) on the trigger" ready to fire at the "enemy's heart".
In a post on his Truth Social platform on Sunday, Trump said: "This morning's attack on Beirut should not have happened, particularly on a special day when we are so close to a Peace Deal with Iran."
Israel has said it was not party to the planned US-Iran deal. Prime Minister Benjamin Netanyahu has differed with Trump over American demands that Israel curb its military action in Lebanon to allow the United States to reach a deal with Iran.
The conflict between Israel and Iran-aligned Hezbollah in Lebanon was reignited by the start of the US-Israeli war against Iran in February.
A senior Iranian official earlier told Reuters that, under the terms of the draft deal, the United States would agree to release $US25 billion ($A35 billion) of frozen Iranian assets, while Iran would agree not to produce or acquire nuclear weapons.
The official said Iran agreed to maintain the nuclear status quo, including no uranium enrichment or expanding nuclear facilities, until a final deal is reached.
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