The Shi'ite militant group has rejected demands it disarm, insisting its weapons are needed to protect Lebanon from Israel.
Nasrallah's speech was his first since Hezbollah fighters seized several areas of Muslim west Beirut in several days of fighting this month, forcing the Western-backed Cabinet to agree to a political deal designed to give Hezbollah and its allies a veto over government policies.
The Hezbollah leader pledged to comply with a provision of the Arab League-brokered agreement that prohibits the use of arms to achieve political gains. But he warned that the government should not try to use the military against Hezbollah and its allies.
"The resistance weapons should not be used to achieve political gains," Nasrallah told tens of thousands of supporters crowding a playground in south Beirut, speaking by videolink from a hiding place in fear of assassination by Israel.
At the same time, he said, "the state's weapons should not be used to settle accounts with an opposition political party, or in favor of outside parties that weaken Lebanon's strength and immunity in confronting Israel."
Pro-Western political groups, which hold a small majority in parliament, have repeatedly called for a defense arrangement that would eventually integrate Hezbollah's fighters and weapons into the national army.
Hezbollah rejects the idea and also balks at observing a requirement that it disarm included in the UN Security Council resolution that ended a monthlong war between Israel and the militant group in 2006.
Suleiman said Sunday that he supports the UN and its resolutions, although he did not specifically mention the requirement for Hezbollah to disarm. However, he said it was necessary to discuss the future of the group's arsenal.
Nasrallah said Hezbollah strongly supported the agreement signed by Lebanon's rival factions in the Qatari capital of Doha, which will give his Syrian-backed bloc veto power in a new Cabinet. The parliamentary majority had staunchly rejected that power for Hezbollah during 18 months of political stalemate, but gave in after the fighting.
Hezbollah's leader did not gloat over the political victory, saying the country's factions must work together. "The national unity government is not a victory against this majority," he said. "This country cannot rise and continue except through cooperation, consensus, and solidarity."
A gunbattle in downtown Beirut late yesterday underlined the continued tensions, despite an outburst of relief over the political deal. Security officials said supporters of Hezbollah and of the pro-Western government traded shots, leaving nine people wounded.
Nasrallah's speech came a day after Suleiman was elected by parliament and sworn in. His election was the first tangible step in the deal to end the long-running political crisis, which escalated this month into the worst violence since Lebanon's 1975-90 civil war.
Suleiman set to work immediately yesterday, scheduling consultations with lawmakers tomorrow to begin forming the new national unity government, his office said.
