Mahmoud Komati, deputy chief of the Hezbollah's political arm, also told The Associated Press that his group will not lay down arms.
His comments were the first time that a leader from the Shiite militant group has publicly suggested it miscalculated the consequences of the July 12 cross-border raid in which two Israeli soldiers were captured and three were killed.
"The truth is — let me say this clearly — we didn't even expect (this) response ... that (Israel) would exploit this operation for this big war against us," said Komati.
He said Hezbollah had expected "the usual, limited response" from Israel.
In the past, he said, Israeli responses to Hezbollah actions included sending commandos into Lebanon, seizing Hezbollah officials and briefly targeting specific Hezbollah strongholds in southern Lebanon.
Komati said his group had anticipated negotiations to swap the Israeli soldiers for three Lebanese held in Israeli jails, with Germany acting as a mediator as it has in past prisoner exchanges.
He said Hezbollah captured the Israeli soldiers from a military area, but charged that Israelis had taken Hezbollah leaders from their homes at night.
"The response is unjustified," Komati said. He added that the Israeli offensive was planned in advance, and Israel was only "waiting for the right time" to carry it out.
Asked about reports that Hezbollah has been firing Iranian-made missiles on Israel, Komati said: "We don't deny nor confirm. We believe where the weapons come from is irrelevant."
Hezbollah leaders previously have denied that Iran was supplying them with weapons.
Komati said Hezbollah has weapons made in various countries, including the United States, France, China and Russia.
"Some of our fighters carry M16s. So you think we buy them from America?" he asked.
Komati said Hezbollah demanded an immediate end to Israeli attacks before agreeing to negotiate and rejected a plan proposed by Secretary of State Condoleezza Rice during her visit to Beirut.
The plan calls for the deployment of international and Lebanese troops in southern Lebanon to prevent Hezbollah attacks on Israel before a cease-fire.
"No one can talk about politics while the fire rages, and killings occur," Komati said.
He said he didn't want to talk about the issues to be negotiated ahead of a cease-fire, including the deployment of an international force.
But he was adamant about Hezbollah's refusal to disarm because of what he said was Israeli occupation of Lebanese land, the "threat of Israeli aggression" and the Lebanese held in Israeli jails.
Meanwhile, Syria's ambassador to the United States said Tuesday all Syrian intelligence agents had left Lebanon along with Syrian troops and that Syria was not providing Hezbollah militia with missiles.
The envoy, Imad Moustapha, also stated the United States, driven by ideologues and lobbyists, is in lockstep behind Israel in its 2-week-old battle with Hezbollah while promoting diplomacy unlikely to succeed,
The troops were withdrawn last year under U.N. Security Council pressure, but doubts have persisted that Syria ended its intelligence presence as a means of maintaining influence in Lebanon. But Moustapha said flatly: "We do not have a single soldier or agent in Lebanon."
Hezbollah has its own sources of arms, Moustapha said, while saying that ideologues in the Bush administration and pro-Israeli lobbyists are driving U.S. policy support for Israel to unprecedented levels. "What Israel says is immediately adopted" by the administration, he said. "Whatever Israel wants becomes immediate U.S. policy in the Middle East."
Israel holds 9,000 Arab prisoners in its jails and yet is projected as "an angel of peace." , Moustapha said.
While Syria supports Hezbollah and also the Palestinian group Hamas, Hezbollah is "an autonomous movement" and "we are not engaged; we are not involved in logistics," he said.
"We do not believe in Syria that Hezbollah needs any military support from Syria," Moustapha added.
And, he said, "Hezbollah has not asked us for any military help," while in the meantime the United States supplies Israel with weapons that is destroying Lebanon and killing women and children.
The United States has long alleged the Iran is Hezbollah's principal source of weapons, with shipments made through Damascus airport.
In the meantime, he said, the United States has not talked at all to the Syrian government and he suggested that current U.S. diplomatic efforts would not succeed. For one thing, Moustapha said, Lebanon would immediately "disintegrate" if required to move troops into the south and disarm Hezbollah.
Deriding U.S. efforts on several fronts, including humanitarian aid, he said, "I don't know which cargo will reach the Middle East first, the blankets or the laser bombs (for Israel)."
By contrast to lack of U.S. contact, the ambassador said Syria had been in touch with several European governments and President Bashar Assad had talked to U.N. Secretary-General Kofi Annan.
On Monday, the administration announced a $30 million (euro23.7 million) package for battered Lebanon that includes medical supplies and blankets.
Israel, meanwhile, is pressing its foray into Lebanon, with the assistance of American-made weapons. The only nation with influence on Israel is not using its leverage to promote an end to the fighting based on an exchange of prisoners held by Israel for two captured Israeli soldiers held by Hezbollah, he said.