"Regarding Iran's nuclear program, they will either reach an agreement or disagree and the situation heads to war," Nasrallah told hundreds of supporters in a rare public appearance in a giant hall south of Beirut to attend a Shiite Muslim religious ceremony.
"If war breaks out, everyone should be worried but others should be worried more than us," Nasrallah said.
"If an understanding is reached between Iran and the West over the nuclear program, our side will be stronger locally, regionally and internationally," Nasrallah said. He also warned Arab countries against betting on the fall of Syrian President Bashar Assad's government, saying that they will be proven wrong.
Nasrallah stood in front of hundreds of supporters who pushed forward to see him while chanting "at your service Nasrallah."
Nasrallah has made few public appearances since his group fought a 34-day war with Israel in 2006 for fear of assassination by Israel.
In his first public appearance since Aug. 2, the black-turbaned Shiite cleric also said that his arch-enemy Israel is happy to see Sunni and Shiite Muslims killing each other.
Nasrallah usually gives his speeches from secret locations and speaks through a television link.