"The Americans allowed the elections and the formation of parliament and a government so that they get an Iraqi legitimisation of the occupation," he said, referring to a reported Iraqi-American agreement that would allow the US to have a permanent presence in Iraq.
The speech by Nasrallah, aired over a video link to supporters, was part of celebrations to mark eight years since Israeli forces withdrew from southern Lebanon.
In downtown Beirut, security officials said at least nine people were injured during the celebrations on Monday night.
Supporters of the ruling coalition and opposition loyalists traded insults before engaging each other with arms late on Monday.
The Corniche Mazraa, where the shooting took place, is an avenue separating Shia and Sunni areas of Beirut and was the scene of fighting earlier this month.
The fighting came a day after Michel Sleiman, the former chief of the Lebanese army, was elected Lebanon's new president.
Sleiman was elected in a parliamentary session after Sheikh Hamad bin Khalifa Al-Thani, the emir of Qatar, helped broker a deal to end a dispute between rival political factions in Lebanon.
Nasrallah welcomed Sleiman's election as president, calling it a new chapter for Lebanon.
"The election of Michel Sleiman brings hope to the Lebanese of a new era and a new beginning," he said.
"His inaugural speech expressed the spirit of consensus that he promised to act upon in the upcoming period ... And this is what Lebanon needs."
Amal Saad-Ghorayeb, a political analyst and expert on Hezbollah, told Al Jazeera that Nasrallah's speech was "quite historic and strategic".
"On the one hand, many people expected him to be more apologetic about the events [clashes between pro- and anti-government fighters] of the last two weeks, but he was quite assertive," she said.
"For example, he talked not only about a defence strategy but a liberation strategy for Lebanon, in relation to the Shebaa Farms region [which is still occupied by Israeli forces]."
Zeina Khodr, Al Jazeera's correspondent in southern Beirut, said Nasrallah praised the resistance against Israel in the early part of his speech.
"He was giving credit to the resistance that actually led to the Israeli withdrawal from Southern Lebanon, even giving examples from Palestine and Iraq," he said.
But Khodr also said that he had sought to downplay suggestions that recent clashes in Beirut between pro- and anti-government forces were a sign of a growing sectarian divide in Lebanon.
"He said that in every country, there is disagreement - those who support resistance and those who do not," she said.
"He is trying to show that the battle and the power struggle in Beirut was not a Sunni-Shia clash - it was simply a power struggle between those who support the resistance and the other, who do not believe in the resistance's weapons," she said.
Appeal for reconciliation
Nasrallah's speech came after Lebanon's 127-member cabinet voted overwhelmingly in favour of Sleiman becoming president on Sunday.
In his inaugural speech on Sunday, Sleiman appealed to Lebanese political factions to work together to avoid internal strife.
Nasrallah said on Monday that Hezbollah did not want to take over the country or undermine political institutions.
|Sleiman was elected Lebanon's president after|
a deal was brokered in Qatar [AFP]
"I am speaking as Hezbollah - we don't want power or authority, we don't want to rule Lebanon, we do not want to impose our thoughts on the Lebanese," he said.
"They call us the party of wilayat al-faqih," he said, refering to accusations that Hezbollah wants to impose an Iranian-style regime in Lebanon.
"The Lebanon wilayat al-faqih means the Lebanon of diveristy and pluralism ... we shoud preserve it as such."
Lamis Andoni, Al Jazeera's Middle East analyst, said Nasrallah's speech, in regard to Lebanese politics, was conciliatory in tone.
She said: "Nasrallah is aiming to recast himself as a nationalist leader and distance himself from the sectarian overtones that have marred the recent fighting."
"His commitment to a pluralistic Lebanon reflects his keen awareness that recent confrontations have fuelled secterian fears and widened the divide."
"However, Nasrallah did not compromise on rejecting any attempt, even if it carried out by the Lebanese army, to disarm Hezbollah."