Iran's chief negotiator Mohammad Bagher Ghalibaf on Sunday warned the United States against making threats at the Islamic republic, vowing that "our armed forces are ready to respond".

U.S. President Donald Trump said Sunday in a surprising statement that "Iran must immediately stop their highly paid PROXIES in Lebanon from causing trouble," apparently referring to Iran-backed Hezbollah.

Cautious calm has been engulfing south Lebanon since Saturday, after Israel's political leadership ordered its army to cease its operations, reportedly following intense U.S. pressure to do so.

U.S. Vice President JD Vance has said that Lebanon is one of "two big things" that will be discussed in the negotiations with Iran, as he departed from Washington for Switzerland.

Israeli Prime Minister Benjamin Netanyahu and Defense Minister Israel Katz on Saturday ordered the Israeli army to halt its operations in Lebanon while maintaining its positions, Israeli reports said.

Pakistani Interior Minister Mohsin Naqvi, who is currently visiting Iran, will convey messages to Tehran regarding the nuclear negotiations, specifically relating to the thorny issue of Lebanon, sources told Al-Arabiya television.

Israel carried out deadly strikes in south Lebanon on Saturday and Hezbollah maintained it had the right to respond, hours after the United States announced a renewed ceasefire in fighting that had strained a fledgling deal with Iran.

Israel and Hezbollah have agreed a ceasefire that begins 4pm Friday Beirut time, a U.S. official said Friday, after deadly new exchanges in Lebanon put the deal to end the Middle East war under strain.

The U.S. has "relayed" to Iran that Israel will not further escalate its attacks in Lebanon as the Trump administration seeks to get high-stakes nuclear talks with Iran back on track, a source familiar with the matter told CNN.

Iran has informed Hezbollah that it will not continue the negotiations with the US without a comprehensive ceasefire in Lebanon, Hezbollah MP Hassan Fadlallah said.

Israel’s military struck targets throughout southern Lebanon overnight into Friday and Hezbollah reported intense fighting in the area, threatening the nascent agreement between Iran and the United States to end their war. Lebanese media reported at least 18 people killed in the strikes, and Israel said four soldiers died, vowing to make Hezbollah pay a heavy price.