U.S. Vice President JD Vance arrived in Islamabad on Saturday for talks with Iran that the Pakistani premier hosting the warring sides called a "make or break" effort to permanently halt weeks of fighting in the Middle East.

Iran demanded a truce in Lebanon and the release of its blocked assets on Friday as U.S. Vice President JD Vance warned Tehran not to "play" Washington, casting doubt on planned ceasefire talks in Pakistan.

Iran's new supreme leader Mojtaba Khamenei said in his latest written message the Islamic republic did not want war with the United States and Israel, but would protect its rights as a nation, state television reported Thursday.

U.S. President Donald Trump on Thursday accused Iran of doing a "very poor job" of allowing oil through the Strait of Hormuz and of breaching the terms of their two-week ceasefire agreement.

In a barrage of social media posts that sparked fresh fears for the shaky truce, Trump also warned Iran against imposing a toll for ships passing through the crucial waterway.

Pakistan was poised on Friday to host Iranian and U.S. delegations for negotiations in its capital, although Tehran's participation remained uncertain after deadly Israeli strikes on Lebanon threatened this week's temporary truce.

U.S. President Donald Trump told NBC News on Thursday he was "very optimistic" about a peace deal with Iran after their ceasefire, and that Israel was "scaling back" strikes in Lebanon.

U.S. Vice President JD Vance on Wednesday urged Iran not to let the fragile ceasefire deal fall apart over Israel's attacks on Lebanon, days before he is due to lead talks with Tehran in Pakistan.

U.S. President Donald Trump said late Wednesday that U.S. forces deployed near Iran would remain stationed in the area until a "real agreement" is reached, as Washington enters a fragile two-week ceasefire with Tehran.

Iran's ambassador to Pakistan deleted a social media post saying an Iranian delegation would arrive in Islamabad on Thursday night, a move an embassy official later told AFP had been sent prematurely.

Iran's parliament speaker said Wednesday that a ceasefire and talks with the United States were "unreasonable" because of violations of Tehran's 10-point truce plan, including continued attacks in Lebanon, a drone entering Iranian airspace and a denial of the country's right to enrichment.