Iran's parliament speaker on Friday set a ceasefire in Lebanon and the "release of Iran's blocked assets" as pre-conditions for the start of negotiations with the United States.

"Two of the measures mutually agreed upon between the parties have yet to be implemented: a ceasefire in Lebanon and the release of Iran's blocked assets prior to the commencement of negotiations," Mohammad Bagher Ghalibaf wrote in a post on X in English.

"These two matters must be fulfilled before negotiations begin."

Ghalibaf made the announcement shortly after US Vice President JD Vance had boarded a plane to fly to Islamabad for talks on transforming a two-week ceasefire agreed between the US and Iran into a permanent truce.

Ghalibaf and Foreign Minister Abbas Araghchi were expected to lead the Iranian delegation in the Pakistani capital.

"If they're going to try to play us, then they're going to find the negotiating team is not that receptive," Vance warned.

Since the truce was first announced on Wednesday, Iran has maintained that it included Lebanon, where Israel's war against Lebanon has killed nearly 1,900 people since the start of March.

Pakistani Prime Minister Shehbaz Sharif, the main mediator between Iran and the US, had said Lebanon was part of the deal -- and it was one of Iran's demands in its 10-point peace plan presented to Washington.

But the White House has denied that the two-week deal included Lebanon, while Vance called it a "misunderstanding" on Wednesday and "nothing to do with" Tehran.

Unblocking frozen Iranian assets had not previously been set publicly as a pre-condition for talks, although full sanctions relief is another of Iran's 10 demands.