Ehud Olmert, the Israeli prime minister, told parliament that Hezbollah had been driven underground.
"These people will not be left alone, we will continue pursuing them anywhere all the time and we do not intend to apologise or ask anyone's permission," he said in a televised address.
"They will not get off free. We will continue to pursue them everywhere and any time."
After Olmert's speech, Benjamin Netanyahu, head of the opposition Likud Party, said there were many failures during Israel's conduct of the war.
"There were many failures, failures in identifying the threat, failures in preparing to meet the threat, failures in the management of the war, failures in the management of the home front."
Left-leaning critics then criticised Olmert for sending about 30,000 troops into south Lebanon even as a UN resolution to halt the fighting was agreed after days of negotiations.
Opinion polls show that many Israelis believe that Israel failed to defeat Hezbollah despite its vastly superior military might.
Olmert acknowledged "shortcomings" and said he bore full responsibility.
He accused critics of sniping at the government but said: "We do not intend to apologise."
Three opposition MPs were removed from the session for heckling.