Palestinian sources have also described some deaths in the conflict as being people who formed a "human shield."

But former Palestinian adviser Diana Buttu told "The Lead with Jake Tapper" that she does not believe "people are going to listen to somebody who says stay inside while your house is being bombed."

Hamas, the Palestinian militant group that controls Gaza, regularly uses sites and facilities populated by civilians.

"The leadership of Hamas and the other organizations has chosen -- at a time when they are using the population of Gaza as human shields -- to hide under ground, to flee abroad and to deliberately put civilians in the line of fire," Netanyahu told a Cabinet meeting Sunday.

"This is the entire difference between us and Hamas -- we are using defensive systems against missiles to protect the residents of Israel, and they are using the residents of Gaza to protect arsenals of missiles. Nothing better underscores the difference in this campaign. Israel is a democracy that is fighting -- in a legitimate and focused manner -- against unbridled terrorists," he said.

The Palestine Liberation Organization, meanwhile, announced that it will ask the United Nations Committee on the Elimination of Racial Discrimination, at its annual meeting in August, to designate Israel as an "apartheid state." And Palestinian Authority President Mahmoud Abbas will ask the United Nations "to officially put the State of Palestine under the UN international protection system," the PLO said.

Israel raids missile site

Israeli forces briefly entered Gaza early Sunday and raided a missile launching site, an Israeli military source said. It marked the first time Israeli forces have acknowledged they've entered Gaza in the current conflict.

During the incursion, which lasted about half hour, both sides exchanged gunfire at the launch site, the source said.

Four Israeli soldiers suffered light injuries, but all the troops returned home safely, the source said.

The source declined to comment on whether the mission achieved its objective.

It likely won't be the last mission of this type, an Israeli military spokesman told CNN's Wolf Blitzer.

"We can expect these type of activities taking place," IDF spokesman Lt. Col. Peter Lerner said. "Special ops that happen usually below the radar, in and out, swift missions, quickly, concise and very precise at what they're doing, to get that added value to safeguard Israeli lives."

Lerner would not give specifics, but said leaflets had warned residents of one town in Gaza to evacuate ahead of military action. He said the area was the source of many rockets fired at Israel.

Israel: 'What would you do?'

Throughout the conflict, Israel has warned Gaza residents of upcoming attacks targeting militants and terrorist infrastructure. On Twitter on Sunday, the IDF posted: "To warn civilians of an impending strike, the IDF drops leaflets, makes personalized phone calls & sends SMSes. How many militaries do that?"

"Sirens heard across (Israel). Gaza terrorists are firing barrages of rockets. Israel is under attack," the IDF posted, with a photo asking "What would you do?"

Another tweet Sunday showed large trucks. "As rockets fall on Israel, we keep our crossing to Gaza open. 59 truckloads of goods are about to reach Palestinians," the post said.

Hamas posted Saturday on its Twitter feed that it was going to strike Tel Aviv. "Palestinians are defending themselves," the group posted Sunday, with a video that it said showed it targeting a tank.

Hamas also tweeted that the "death toll rises to 162 martyrs" from Israeli airstrikes.