When it comes to the escalating border violence between Israel and the Gaza strip, Obama administration officials have made the U.S. position clear: Hamas is to blame.

Aboard Air Force One, White House Press Secretary Jay Carney told reporters that the administration strongly condemns the on-going rocket fire from Gaza. Carney lamented the civilian casualties among both the Israelis and Palestinians over the last few days, but said it is Hamas, a U.S.-designated terror group, which governs the Gaza strip, that is instigating the violence.

"Hamas claims to have the best interest of the Palestinian people at heart, yet it continues to engage in violence that is counterproductive to the Palestinian cause," Carney said. "Attacking Israel on a near daily basis does nothing to help Palestinians in Gaza or to move the Palestinian people any close to achieving self-determination."

This is the worst flare-up of violence between Israel and the Palestinians in several years. After contending with a steady stream of missiles being fired by Hamas into Southern Israel over the course of this year, the Jewish state launched its own offensive on Wednesday, killing Ahmed Jabari, a Hamas military leader. In retaliation, the group launched nearly 150 more rockets at Israel on Thursday. The attack killed three Israelis in the southern town of Kiryat Malakhi, with rocket fire reaching Israel's largest city of Tel Aviv.

In just the last two days at least 15 Palestinians have reportedly been killed, in addition to the Israeli casualties. There are also reports that Israel may be preparing for a ground operation as it moves troops near the border. A ground incursion by Israel into Gaza could signal the beginning of an all-out war.

When asked about the possibility of a ground offensive, Deputy National Security Adviser Ben Rhodes told reporters on a conference call that the United States respects Israel's right to defend itself, but would not like to see the conflict escalate further.

"Our view is the Israelis have a right of self-defense when their citizens are faced with the threat of indiscriminate rocket fire from within Gaza. Ultimately it's up to the Israeli government to make a determination about how they are going to carry out their military objective," said Rhodes. "But we've also said the best course of action would be for there to be a general de-escalation of the violence, but the onus is on Hamas and those with influence over Hamas to help bring about that de-escalation so we don't see a widening conflict. "

An Israel Defense Forces spokesman told ABC News that there are no immediate plans to begin a ground operation in Gaza, though the military is prepared to do so if needed.

"At this point, we have not received directives from the political echelon to embark on a ground maneuver in the Gaza Strip," the spokesman said. "We are prepared for the possible expansion of the operation if necessary but are currently engaged in the aerial phase that has included pinpoint targeting of approximately 250 sites. These sites include medium- and short-range rockets, launching pits, storage depots and senior terrorist leaders."

Both President Obama and Secretary of State Hillary Clinton have contacted leaders in Egypt, Turkey and other European allies who have influence with Hamas.

Egypt, whose new governing Muslim Brotherhood party has a relationship with Hamas, also has a binding peace treaty with Israel. Under the previous regime, led by Hosni Mubarak, Egypt was one of the staunchest and most reliable U.S. allies in the region. State Department Deputy spokesperson Mark Toner told reporters today that the administration is imploring Egypt to use its regional influence to help stop the escalating conflict.

But Egyptian officials have publicly said that the Palestinians have the right to self-defense, and diplomatic relations between Israel and Egypt have been strained over the violence. This week Egypt's ambassador to Israel returned to Cairo for consultations, and Israel's ambassador to Egypt also returned to Jerusalem before the offensive was launched. On Friday Egypt's prime minister, Hesham Kandil, will travel to Gaza to speak with Hamas officials.

Toner refused to characterize the substance of the conversations between U.S. and Egyptian officials over the conflict, but said that both countries remain in agreement that the violence needs to end.

"There is a very clear path here to ending the violence and that's for the rocket attacks to stop, so we would hope that that's a message that would be delivered," he said.