BEIRUT, Lebanon — Hezbollah’s leader offered yesterday to stop rocket attacks on northern Israel in return for an end to airstrikes throughout Lebanon.

However, Sheik Hassan Nasrallah also vowed to fire rockets into Tel Aviv if Israel strikes Beirut proper. Israeli warplanes have repeatedly bombarded Hezbollah strongholds in southern suburbs of Beirut.

“If you bomb our capital Beirut, we will bomb the capital of your usurping entity …We will bomb Tel Aviv,” he said in a taped televised speech.

In issuing the threat, Sheik Nasrallah offered his first opening toward diminishing the three-week-old conflict, which has taken more than 500 Lebanese lives and killed more than 50 Israelis.

“Any time you decide to stop your campaign against our cities, villages, civilians, and infrastructure, we will not fire rockets on any Israeli settlement or city,” he said in a taped video statement broadcast on Hezbollah’s Al-Manar TV and carried simultaneously on all other Lebanese and Arab satellite channels.

Speaking directly to Israelis, Sheik Nasrallah said, “The only choice before you is to stop your aggression and turn to negotiations to end this folly.”

Parts of the speech were carried on Israeli television channels, with Hebrew translation.

Sheik Nasrallah said his forces were succeeding in inflicting “maximum casualties” on Israeli ground troops and that his guerrillas were “fighting until the last breath and last bullet.”

Sheik Nasrallah acknowledged Israeli advances deeper into Lebanon but said his guerrillas were not trying to hold ground. “We are fighting a guerrilla war. Our policy is not to hang onto geography … It is beneficial for us to allow them to advance to the entrances to villages. This is our goal. Our goal is to inflict maximum casualties and damage to the capabilities of the enemy, and we are succeeding,” he said.

Sheik Nasrallah said Hezbollah’s command and control structures and rocket forces remained intact.

Israel claims to have killed more than 300 Hezbollah fighters since the conflict began July 12. The guerrilla group has acknowledged losing only 46 men.

In his 45-minute address, Sheik Nasrallah said he held President Bush responsible for the war in Lebanon and said America was blocking a cease-fire.

“Lebanon will never be pro-American or pro-Israeli. Lebanon will not be part of the ‘new Middle East’ that Bush and Condoleezza Rice want,” he said.