"We possess and we will continue to possess rockets that can hit any area in occupied Palestine if Israel attacks Lebanon."
Nasrallah did not attend the rally, due to security concerns but his speech was relayed on a giant screen set up in the town's main square.
Most of his speech concentrated on the supposed objectives of Israel during the 2006 war, which he said were not achieved.
He said that the group's steadfastness in front-line villages had led to the failure of the Israeli attack.
This had prevented Israel from destroying Hezbollah's military structure and securing the release of two of its captive soldiers.
He said: "The enemy [Israel] has even failed to return the two prisoners."
He dismissed unnamed pressures to release the two Israeli soldiers, whose capture, along with the killing of three other soldiers on patrol, sparked the war on July 12, 2006.
Israel invaded southern Lebanon after the capture, unleashing a massive bombing campaign that destroyed most of the country's infrastructure and shook its fragile political system, but failed to eradicate Hezbollah.
The group still enjoys widespread support, particularly from its Shia constituency.
The Israeli offensive killed more than 1,000 Lebanese, most of them civilians, according to tallies by the Lebanese government, human rights groups, and The Associated Press.
Hezbollah launched nearly 4,000 rockets at Israel during the war, which killed an estimated 119 Israeli soldiers and 39 civilians.
Amid Lebanon's growing political and sectarian difficulties, Nasrallah called for national unity and said his group would seek harmony among the Lebanese "regardless of their sects, movements or origins".
|Supporters commemorated Hezbollah fighters|
who died in last summer's war
Hezbollah's critics say the group triggered the current political crisis by stepping out of a coalition government.
Zeina Khodr, Al Jazeera's Lebanon correspondent, said: "The divide is deep and there are real fears that without political reconciliation, the country may witness internal violence."
Saturday's rally was also held to commemorate Hezbollah's fighters who died in the fighting with Israel.
Amal, an attendee of the rally, told Al Jazeera that she came to say that without Hezbollah, she would never have been able to return to her home.
Khodr, at the rally in Bint Jbeil, said: "For people here, Bint Jbeil has symbolic importance. In the year 2000, Nasrallah delivered a victory speech here when Israel ended its 22-year occupation.
"Today, the town has yet another meaning. Some of the fiercest ground battles took place here during the war last summer and the Israelis weren't able to advance in the town."
'New Middle East'
Nasrallah repeatedly mentioned "a new Middle East" in his speech on Saturday, alluding to comments by Condoleezza Rice, the US secretary of state, who called for such a concept during last year's war.
She described it as a new era of democracy and peace in the region.
Nasrallah told supporters: "The war was supported by the US, Israel, Arab countries and the international community as a whole.
"The United States wanted to install a Lebanese government that would implement its plan in the region."
Hezbollah and other critics say the US' plan aimed to reinforce Israel.