President Shimon Peres on Sunday rejected the possibility of a cease-fire as the IDF pressed its offensive against Hamas militants in the Gaza Strip, but said Israel does not intend to occupy Gaza.

"We don't intend neither to occupy Gaza nor to crush Hamas, but to crush terror. And Hamas needs a real and serious lesson. They are now getting it," Peres said in an interview on the ABC News program "This Week."

Peres also brushed aside the chances of a cease-fire to bring the fighting to a halt.

"We shall not accept the idea that Hamas will continue to fire and we shall declare a cease-fire. It does not make any sense," Peres said.

"We were careful. We were restrained. We waited. We gave them many chances," he said.

"They cannot explain why they are shooting...and they cannot hide that they are acting by orders from Iran. Iran has two satellites in the Middle East, the Hezbollah in Lebanon and Hamas in Gaza."

Earlier Sunday, Prime Minister Ehud Olmert said the Israel Defense Forces' ground invasion of the Gaza Strip was unavoidable.

"We did not reach this conclusion lightly," Olmert told his ministers at the beginning of the weekly cabinet meeting in Jerusalem.

"For many months, we gave the cease-fire a chance in the hope of avoiding a wide-ranging military operation. Our hopes were dashed."

The prime minister added that the ground operation was "designed to establish our aspiration to change the security reality in the south."

"IDF forces have went into Gaza to strike at the military infrastructure that Hamas has established and to take control of the areas from which most of the missiles have been fired at Sderot, Ashkelon, and Ashdod."

Addressing mothers of IDF soldiers, the prime minister said his thoughts were constantly with them.

"I asked myself and my ministerial colleagues if there was some other step, outlet or effort that we had not yet tried before sending our boys into a place fraught with such risks ? from which some of them may not return," he said.

"Today I can look each and every one of you in the eye and say we did everything we could before launching this operation." Olmert added. "It was unavoidable."

Olmert further stated that Israel will not allow a humanitarian crisis to occur in Gaza.

"Israel is not fighting Palestinians living in Gaza. They are not our enemy. They are victims of violent and cruel oppression," he said.

"We will aid with food and medical supplies as any moral and enlightened country must."