The 60-year-old prime minister also predicted that the outcome of the Lebanon fighting would create "new momentum" for Israel's plan to separate from the Palestinians by withdrawing from much of the West Bank.
He had harsh words for Syrian leaders, calling them "reckless," "immature," and promoters of terror.
"Israel will stop fighting when the international force will be present in the south of Lebanon," Olmert said. "We can't stop before because if there will not be a presence of a very effective and robust military international force, Hizbullah will be there and we will have achieved nothing."
Washington is leading efforts to put together a beefed-up international force that could help the Lebanese army take control of south Lebanon after Hizbullah is pushed northward. But disagreements have emerged between the US and Europe over the issue, with the latter favoring an immediate cease-fire, even before an international force is deployed.
It's not clear how long it will take to put together a multinational force. The Bush administration on Tuesday claimed progress on setting up the force, with Secretary of State Condoleezza Rice saying an agreement on how to end the fighting was possible within days, not weeks.
In the interview, Olmert said the force should also be deployed along the Lebanon-Syria border "to prevent the smuggling of arms from Syria to Lebanon as they are doing now."
The conflict, which began after Hizbullah crossed into Israel, capturing two soldiers and killing three others, has already killed at least 532 Lebanese and 54 Israelis.
Photographs of the two captured soldiers, along with a photo of another Israeli serviceman seized by Hamas in Gaza on June 25, adorned a table in front of Olmert's desk. The prime minister sat beside a large Israeli flag in his wood-paneled office, which also had photos of past Israeli leaders including Menachem Begin, Yitzhak Shamir, Yitzhak Rabin and Ariel Sharon.
Olmert said his government favors finding a diplomatic solution to the Lebanon conflict but that "Israel is not afraid of fighting."
"No one can intimidate Israel. No amount of rockets and missiles can stop Israel from exercising its fundamental right to self defense," he said, referring to the nearly 2,000 Hizbullah rockets that have fallen on northern Israel since fighting began.
Turning to Syria to help solve the crisis would be useless, he said.
"I don't see that Syria is ready or is even prepared to avail itself of any act of moderation," Olmert said.
Some Mideast observers have said that Syria would be a good address for talks because of that country's sway over Hizbullah and the fact that its alliance with Iran, another major Hizbullah supporter, is based more on convenience than shared ideology.
Olmert dismissed criticism of US President George W. Bush's refusal to talk to Syria or any other regime it dislikes.
"He (Bush) is doing the most obvious thing. He's fighting the enemies of freedom, he's fighting the enemies of democracy and he's fighting supporters of terror."
Olmert also defended Israel's military operations in Lebanon that have killed more than 460 civilians, saying Hizbullah is targeting Israeli civilians while Israel is trying to avoid killing Lebanese civilians.
"Every time we kill a civilian we consider it as a failure and we are very sorry for it," he said.
Israel's simultaneous offensives in Lebanon and in the Gaza Strip have raised questions about Olmert's ability to go forward with what was supposed to be the cornerstone of his governing agenda: withdrawing from the West Bank in order to secure a long-term Jewish majority for Israel.
"I'll surprise you," Olmert said. "I genuinely believe that the outcome of the present (conflict) and the emergence of a new order that will provide more stability and will defeat the forces of terror will help create the necessary environment that will allow me ... to create a new momentum between us and the Palestinians."
"We want to separate from the Palestinians," he added. "I'm ready to do it. I'm ready to cope with these demands. It's not easy, it's very difficult, but we are elected to our positions to do things and not to sit idle."
Olmert, a lawyer and former mayor of Jerusalem, has been in power for only four months.
"It's true that I am a new prime minister, relatively speaking," he said. "Though in Israel, every day is like a year in other places."
