Al Jazeera -- Sayyid Hassan Nasrallah called on Hezbollah's allies on Monday to put in place a united strategy "in the field" to confront Israel.
His speech came as thousands of Hezbollah supporters demonstrated in Beirut, chanting "Death to America!" and "Death to Israel!" in protest against President Donald Trump's decision to recognise Al-Quds (Jerusalem) as Israel's capital.
Hezbollah, an Iran-backed Lebanese Shia political bloc with a powerful military wing, has been fighting in Syria alongside regional allies to defeat both anti-government rebels and ISIS.
Nasrallah said he hoped the "foolish [US] decision" would mark the "beginning of the end" of Israel.
Days of protest
Nasrallah asked Hezbollah supporters to continue protesting against the US move.
Nasrallah described Trump's decision as yet another aggression against the Palestinian cause whose aim was to strip Palestinians of their rights.
Nasrallah had called for the demonstration last week after Trump made his announcement in a televised speech on December 6.
The move has been heavily denounced and has prompted days of protest across the Middle East and elsewhere.
Lebanon is home to over 450,000 Palestinian refugees, who make up nearly 10 percent of the country's population.
Israel fought a war against Hezbollah in Lebanon in 2006 that killed more than 1,200 Lebanese, mostly civilians, and 120 Israelis, most of them soldiers.
Israel withdrew its forces from southern Lebanon in 2000, ending a 22-year occupation, but the two countries remain technically at war and there have been occasional skirmishes on the border.