A top US official on Sunday dismissed a proposal for reopening the Strait of Hormuz presented by Iran as "cynical" and indicated it was a non-starter for Washington.

Iran's truce plan, announced by Foreign Minister Abbas Araghchi at the United Nations earlier this week, calls for the release of frozen Iranian assets, the lifting of sanctions on Iranian oil and an end to the US naval blockade in order for the key waterway central to the world's energy supplies to be opened.

"This was, I think, a pretty cynical attempt to put something on the table that they knew was unacceptable," US Ambassador to the UN Mike Waltz said on Sunday in an interview with NBC. "To ask for the release of the blockade, the sanctions, international sanctions, and access to billions in assets just to talk."

US President Donald Trump rejected the deal on Saturday, stating that Iranian leaders wanted the deal because "they are losing so badly."

"I think it's kind of common sense that the president doesn't have a lot of confidence this time after we just tried a few months ago, but at the end of the day, of course, the president this has to end in some type of arrangement," Waltz said. "But he's going to leave all options on the table to get there."

Speaking on NBC shortly after, Araghchi denounced what he described as "old, unproved accusations" made by Waltz.

"We are ready to open the strait if certain things are done by the US and these certain things are not new, have not come from the space," he said. "These are our rights that we want to be respected."

Araghchi struck a pessimistic tone regarding the prospect of a deal.

"There is also always hope for diplomacy, but we have no reason, to be honest with you, we have no reason to come back to diplomacy and engage with this administration once again because of their behavior in the past two years," he told NBC.

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