Senior US Republicans have launched a rare public rebuke of President Donald Trump over the reported terms of the ceasefire agreement with Iran, warning they include major concessions that would strengthen Tehran and undermine Israel.

The criticism intensified on Sunday after Trump said a memorandum of understanding to end the US-Israeli war on Iran had been "largely negotiated" and was awaiting finalisation.

Trump said the agreement would include reopening the Strait of Hormuz, the vital global energy chokepoint that Iran has effectively controlled since the war began in late February.

Her did not mention Iran's nuclear programme, despite repeatedly insisting that Iran would not be allowed to attain nuclear weapons.

Iran's Foreign Ministry spokesperson Esmaeil Baghaei said on Saturday that Tehran was finalising a memorandum of understanding that would serve as an initial framework agreement lasting between 30 and 60 days.