"We have the right, the entire right to possess any weapon and among it the air defence weapon and we have also the right to use this weapon when we need it," Nasrallah told a crowd of supporters in the Lebanese capital Beirut.
But he refused to confirm or deny Israeli reports that Hezbollah has acquired anti-aircraft weapons from Syria, Lebanon's eastward neighbour.
Nasrallah said that an air defence system would challenge Israel's air, military and naval strength and change the balance of power in the region.
Israel's last large-scale attack on Lebanon came in July 2006, when it struck Hezbollah targets in response to a cross-border raid by the Lebanese resistance group.
More than 1,200 people in Lebanon, most of them civilians, were killed during the 34-day conflict, while 159 Israelis died as a result of the war.