Thousands filled the streets in Beirut to hear the Hezbollah leader speak out against the controversial video. (@LucyKafanov/Twitter)

"The world should know our anger will not be a passing outburst but the start of a serious movement that will continue on the level of the Muslim nation to defend the Prophet of God," said Hezbollah leader Sheik Hassan Nasrallah.

Tens of thousands of Hezbollah supporters flocked to Beirut, chanting anti-American and anti-Israel slogans of "America, America, you are the greatest Satan" and "Israel, Israel, you're the enemy of Muslims."

Monday's protest is the latest in a string of Middle East demonstrations denouncing the controversial film "Innocence of Muslims," which depicts the Muslim Prophet Mohammed as a womanizer and child molester. The online video was paid for by private U.S. funds and has since sparked widespread discontent and violence throughout the Muslim world.

Nasrallah rarely makes public appearances, a move the LA Times said could signal Hezbollah's desire to align itself as a moral force in the Arab world. Despite pledging support to Syrian President Bashar Assad, Nasrallah called the film's issue "more serious than what's going on in Syria," citing the country's civil unrest that has reportedly left thousands of civilians dead.

The rally remained upbeat and non-violent, a contrast to the bloodshed spilled elsewhere in the Middle East. Last week U.S. Amabassador Chris Stevens and three Americans were killed in an attack on the U.S. consulate. Similar attacks were launched on embassies throughout Asia, Africa and Europe.

The group held the protest in a largely Shiite neighborhood, likely to avoid violence.

The Hezbollah leader vowed the protests will continue until the film is yanked from the Internet and the creators held accountable. He warned the U.S. of "grave" consequences should the film ever show in its entirety. Nasrallah continued, and said all websites that offer the film should be boycotted.

According to the Associated Press, U.S. officials refuse to limit free speech, a move supported by Google Inc. The company refuses to enforce a blanket ban on the YouTube video.

As a precaution to the Lebanon protest, the embassy encouraged U.S. citizens to take additional security measures in preparation for a potential upsurge in violence.

Read more of Neon Tommy's coverage on the Middle East protests here and here.

Reach Supervising Executive Producer Amanda Martinez here.