WASHINGTON: Senior US Senator Carl Levin criticized Egypt's "weak" efforts Sunday to pressure its ally Hamas to reduce tensions in the bloody conflict between Gaza's Islamist rulers and their enemy Israel.

"It's pretty weak so far from what I can tell. The Egyptians have a real interest here in the region not exploding and the peace agreement continuing to be abided by," said Levin, who chairs the Senate Armed Services Committee.

"They're going to have to take some very serious steps diplomatically to make it clear to Hamas that they're going to lose support in the Arab world if they continue these rocket attacks on Israel," he told ABC's "This Week."

Egypt was mediating talks between Hamas and Israel to broker a ceasefire to the conflict that had claimed 64 Palestinian lives in nearly 100 hours of Israeli air raids, and seen three Israelis killed by rockets fired from Gaza.

Washington has urged both Egyptian President Mohamed Morsi and Turkey's Prime Minister Tayyip Erdogan to press Hamas to stop firing rockets into Israel.

Egypt and Turkey have in the past mediated ceasefires and a prisoner exchange between Israel and Gaza's Hamas rulers.

Both countries' relations with the Jewish state have grown increasingly cold over Israeli policy toward the Palestinians.

US President Barack Obama said earlier Sunday that it was "preferable" for the Gaza crisis to be ended without a "ramping up" of Israeli military action, as fears mounted of a new invasion of the Hamas-run territory.

"Israel has every right to expect that it does not have missiles fired into its territory," Obama said.

Levin warned that the crisis could deepen.

"It could escalate and I think the potential is there," he said. "However, President Obama and others are doing their best to see if they can't turn Hamas's attacks off."

Morsi, elected in June after a popular uprising overthrew veteran strongman Hosni Mubarak last year, recalled his ambassador in Tel Aviv after the latest salvo of Israeli airstrikes began and sent his premier to Gaza on Friday in a show of support to Hamas.