Hezbollah leader Hassan Nasrallah gave his annual speech Friday to mark "Al-Quds Day," calling Iran "The only hope left for liberating Palestine and Jerusalem."
Nasrallah's speech was televised and filmed in a hidden bunker and screened in a event in the Dahiya quarter of Beirut. He also said that Iran would be "perverting her own religion" if Tehran agreed to Prime Minister Benjamin Netanyahu's demands that Israel be recognized as a Jewish State.
He also addressed fighting in Syria during the speech saying that "If Syria goes to Hell, Palestine will go to Hell."
Meanwhile, tens of thousands of Iranians chanted "Down with America" and "Death to Israel" during pro-Palestinian rallies nationwide on Friday, as a deadline on talks to reach a deal on Iran's nuclear program was postponed until Monday - the third postponment in two weeks.
The "Al-Quds Day" rallies took place as Iran and six world powers were meeting in Vienna to work out a deal to limit Iran's nuclear program in exchange for easing tens of billions of dollars in economic penalties on the Islamic Republic.
Iranian President Hassan Rouhani made a brief appearance at the rally in the capital, Tehran, but did not mention the nuclear talks that have blown past two extensions and entered the 14th day of the current round on Friday. US Secretary of State John Kerry warned on Thursday that the Americans were ready to leave.
However, a top leader said Friday the US would be making a "strategic mistake" if it pulled out of ongoing negotiations on Tehran's nuclear program.
"If you drive the talks into a dead end then it will be you who will be committing a strategic mistake," Iran's parliament speaker Ali Larijani said at Friday prayers following the rally in Tehran, addressing the US "And its outcome will not benefit you since Iran's nuclear staff are ready to accelerate nuclear technology at a higher speed than before."
At the rally, the hard-line protesters wrapped America, British, Israeli and Saudi flags around pillars and set them ablaze.
Since the 1979 Islamic Revolution, Iran has observed "Al-Quds Day" during the Islamic holy month of Ramadan. Tehran says the occasion is meant to express support for Palestinians and emphasize the importance of Jerusalem for Muslims.
Iran does not recognize Israel and supports anti-Israeli militant groups like Hamas in Palestine and Hezbollah in Lebanon.
Reuters contributed to this report.