The speaker of Iran’s parliament warned Friday that scheduled negotiations to end the war with the United States cannot begin unless Israel halts attacks on Lebanon and unless the U.S. releases Tehran’s frozen assets.

Speaker Mohammad Bagher Ghalibaf issued that ultimatum after an American delegation led by Vice President JD Vance flew to Islamabad for talks with Iran, which reportedly will include Ghalibaf and Iranian Foreign Minister Abbas Araghchi.

Ghalibaf’s conditions strain Iran’s already fragile two-week ceasefire with the U.S., which began Tuesday.

“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,” Ghalibaf said in an X post.

“These two matters must be fulfilled before negotiations begin,” he wrote.

Meanwhile, President Donald Trump has expressed frustration with Iran continuing to block most shipping traffic through the Strait of Hormuz.

The strait is the world’s most vital shipping route for oil. Before the war, 20% of the world’s crude was transported through that passage.

Earlier Friday, Vance told reporters he thinks the negotiations will be “positive,” while warning Iran not to “play us.”

In addition to Vance, the U.S. delegation for the talks includes special envoy Steve Witkoff and Jared Kushner, Trump’s son-in-law and advisor, according to the White House.

“We’re looking forward to the negotiation,” Vance said. “As the president of the United States said, if the Iranians are willing to negotiate in good faith, we’re certainly willing to extend the open hand.”

“If they’re going to try to play us, then they’re going to find that the negotiating team is not that receptive,” he added.

“So we’re trying to have a positive negotiation. The president … gave us some pretty clear guidelines, and we’re going to see.”

In an announcement Tuesday evening, Trump said that the U.S. would agree to a two-week suspension of hostilities subject to Iran agreeing to a complete and immediate reopening of the Strait of Hormuz.

But since then, vessel traffic through the strait remains nearly as tightly throttled as it has been since the war began on Feb. 28.

In a Truth Social post on Thursday evening, Trump fumed, “There are reports that Iran is charging fees to tankers going through the Hormuz Strait — They better not be and, if they are, they better stop now!”

Iran “is doing a very poor job, dishonorable some would say, of allowing Oil to go through the Strait of Hormuz,” the president wrote in a follow-up post. “That is not the agreement we have!”