Speaking via video link for security reasons, Nasrallah said Israeli forces had gone on alert along the border with Lebanon since Saturday when the attack on Gaza began.
He said the Israelis were either taking precautionary measures or preparing for an attack in an attempt to avenge its failure to destroy Hezbollah in 2006.
"We are ready to face any aggression on our land, our country or our dignity," he said.
"We will tell the world we are here, and terrorism and killing cannot intimidate us."
Rula Amin, Al Jazeera's correspondent in Lebanon, said Nasrallah wanted to talk to the Arab people "bluntly and truthfully".
"He said this attack by Israel is part of a larger US-Israeli plan to weaken Hamas, to impose upon the Palestinians and on Hamas to surrender and accept a settlement plan on Israeli terms.
"The harshest words he had were for the Arab regimes. He said some were 'partners in this plot'.
"He quoted Israeli officials saying that the support they were receiving from Arab countries to continue their attacks on Gaza was even stronger than the support received during the time when they were attacking Hezbollah in 2006.
"What he says echoes the sentiments on the Arab street. Today in Beirut, many of the harsh words were not only against Israel, but against Arab governments, who they say have been silent, standing by, and according to some protesters, taking part."
Call to Egyptians
Nasrallah urged Egyptians in their "millions" to take to the streets to force their government to open the country's border with Gaza, where Israel is conducting deadly air raids against Palestinians.
"If the Egyptian people took to the streets by the millions, could the police kill millions of Egyptians?
"People of Egypt, you must open this border by the force of your chests," he said.
The Hezbollah chief also called for a mass rally to be held in his movement's bastion in the Shia southern suburbs of Beirut on Monday in solidarity with the people of Gaza.
"We will tell the world we are here, and terrorism and killing cannot intimidate us," he said.