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.

In leaflets dropped Sunday, the IDF warned residents that it intends "to attack terrorists and terror infrastructures." The leaflets list areas that will be targeted. "Israel is currently attacking, and will continue to attack, every area from which rockets are being launched at its territory."

The leaflets told residents which roads were safe to take and gave a time frame. "The IDF is not interested in hurting you or your family members. These operations are limited and short. Whoever does not adhere to these instructions and does not vacate their house immediately is subjecting their lives and the lives of their children and family to danger," the leaflet said.

The Israeli military said it also drops empty shells on roofs, an operation it calls "roof knocking," to alert civilians that airstrikes are imminent.

The goal of the airstrikes, the military said, is to get Hamas militants to stop firing rockets into Israel.

Hostilities between the two sides escalated this month after the killing of three Israeli teenagers and a Palestinian teen. Neither Hamas nor Israel appears to be backing down.

More than 10,000 Palestinians are displaced and hundreds of thousands have been affected by damage to water infrastructure, said UNWRA, the refugee agency.

Concerns about a ground invasion by Israeli forces are growing, prompting the U.N. Security Council to call for a cease-fire between Israeli forces and Palestinian militants.