NEAR THE ISRAEL-GAZA BORDER (CNN) -- Israel is prepared to significantly escalate its military operation against Palestinian militants in Gaza, Prime Minister Benjamin Netanyahu said Sunday.
The comments come on the heels of reports that the Israel Defense Forces have widened the scope of their effort to stop rocket attacks from Gaza, targeting Palestinian media organizations, government buildings and the homes of Hamas officials in Gaza.
"We are exacting a heavy price from Hamas and the (other) terrorist organizations, and IDF is prepared for a significant expansion of its operations," Netanyahu told reporters shortly before the start of a weekly Cabinet meeting in Jerusalem.
The United States and a number of European countries have put the brunt of the blame for the current crisis on Hamas, saying Israel has a right to protect itself. Arab and Muslim nations, meanwhile, have accused Israel of being the aggressor.
Over the weekend, Netanyahu said he spoke with a number of leaders, including U.S. President Barack Obama.
"In my talks with leaders, I emphasize the effort Israel is making to avoid hitting civilians, and this at a time when Hamas and other terrorist organizations are making every effort to hit civilian targets in Israel," the prime minister said.
Even so, the casualties have been heavily lopsided since Israel launched its offensive on Wednesday in response to persistent rocket attacks that have plagued portion of southern Israel for months.
At least 50 people have been killed in Gaza since the Israeli offensive began, according to Palestinian officials and Hamas media reports.
Among the casualties are 13 children, including a young girl who was killed Sunday in an airstrike that targeted the town of al-Shati in western Gaza, Hamas-run al-Aqsa TV reported. A man was also killed in the strike, according to the news agency.
At least 440 people have been injured in airstrikes, according to Palestinian government and medical officials.
Among those are six Palestinian journalists who were wounded Sunday when Israeli warplanes targeted two buildings that housed Palestinian and Hamas new organizations as well a handful of international news outlets, according to Palestinian government and media reports.
In Israel, the rocket attacks have killed at least three people and wounded 68, including a number of soldiers along the Israel-Gaza border, the Israel Defense Forces said.
Q&A: Gaza strikes could be beginning of ground attack
Leaders across the world have called on Israeli and Palestinian governing bodies to show restraint, fearing at a minimum a possible repeat of Israel's 2008 invasion that left at least 1,400 people dead.
But the crisis showed no sign of abating Sunday despite reports Egypt and France were attempting to broker cease-fires.
French Foreign Minister Laurent Fabius was en route to Israel Sunday "to work out a cease-fire with all parties involved" as part of an effort to de-escalate the conflict, according to a ministry statement.
Egyptian President Mohamed Morsy, meanwhile, said discussions were underway about how to bring about a cease-fire.
"But there are no guarantees at the moment," Morsy said Saturday in Cairo, where he met with Hamas officials and other Arab diplomats.
Morsy did not go into details of the effort, though an Egyptian military official told CNN the nation's intelligence chief, Mohammed Shehata, was spearheading talks with Hamas and Israel.
Shehata contacted Israel and requested it "calm down" the situation, said the military official, a general, who spoke on condition of anonymity because of the sensitivity of the subject matter.
It is not known what, if anything, Israel said in response to the request.
Hamas, however, put conditions on cease-fire talks. Israel must cease its attacks and lift its blockade of Gaza in exchange "for stopping the rockets" targeting Israeli cities, according to a report by the Palestinian Information Center, a Hamas-run media outlet.
Israel is unlikely to consider such a request as it sees the blockade as vital to its national security.
The Israeli government has called up 75,000 reservists, while it simultaneously deployed 30,000 troops to the Gaza border, the IDF said.
"Israel will take all necessary and legitimate measure to defend its citizens, including ground operations," Michael Oren, Israel's ambassador to the United States, told CNN late Saturday.
Israel has been using shelling and airstrikes to target what it describes as rocket-launching sites and infrastructure operated by Hamas and other militant groups.
Hamas' military wing, the Izzedine al Qassam Brigade, claimed to have fired 34 rockets on Sunday, adding to the more than 900 it says
Israel's Iron Dome missile defense system is credited with stopping hundreds of the rockets fired at its cities, but hundreds have gotten by the system.
On Sunday, air raid sirens sent Israelis in the southern city of Ashkelon, a few kilometers from the Gaza border, running for shelters from rockets.
One struck the carport of a home in a residential neighborhood, CNN's Frederik Pleitgen reported.
As clean-up crews worked to remove debris from around the house, another air siren sounded.
Minutes later, the attack was over. The rocket struck some distance where Pleitgen was reporting, though he said there was "definitely an impact."
On the other side of the border, an Israeli airstrike targeted two buildings that housed Hamas-run media as well as international journalists.
Video broadcast on al-Aqsa TV showed people running from the smoldering buildings, while others helped the injured.
The journalists wounded in the attack worked for Palestinian-owned, Beirut-based Alquds TV, according to the Hamas Ministry of Interior.
Q&A: What is Hamas?
CNN's Sara Sidner reported from Gaza City; CNN's Fred Pleitgen reported from southern Israel; and CNN's Chelsea J. Carter from Atlanta. CNN's Kindah Shair, Amir Ahmed, Jessica Yellin, Ben Wedeman and Mohamed Fadel Fahmy contributed to this report.