Israeli television reported Tuesday that a rocket aimed at Tel Aviv was intercepted by its "Iron Dome" defense system after the country carried out airstrikes on at least 100 sites in the Hamas-ruled Gaza Strip as part of a new offensive aimed at halting rocket attacks by militants.

The apparent rocket attack would be the deepest strike by Palestinian militants since Israel launched an offensive in the Gaza Strip.

Air raid sirens went off in the city, which is Israel's commercial capital and about 45 miles north of the Gaza Strip. The Israeli military didn't immediately confirm the report, but an explosion was heard shortly afterward.

The earlier strikes prompted President Obama to urge both sides to exercise restraint.

But the Israeli military said the strikes would help "retrieve stability to the residents of southern Israel, eliminate Hamas' capabilities and destroy terror infrastructure operating against the State of Israel and its civilians."

The airstrikes resulted in five Palestinian deaths and over a dozen injured, Gaza’s Health Ministry said.

"We have repeatedly warned Hamas that this must stop and Israel's defense forces are currently acting to put an end of this once and for all," said Mark Regev, a spokesman for Prime Minister Benjamin Netanyahu.

The Israeli military said "Operation Protective Edge" looks to strike the Islamic Hamas group and end the rocket fire that has reached deeper into Israel and intensified in recent weeks.

The attacks come as tensions have soared over the killing of three Israeli teenagers and the apparent revenge killing of a Palestinian teenager by three Jewish suspects.

Nearly 300 rockets and mortars have been fired at Israel in recent weeks, including a barrage of close to 100 projectiles on Monday alone, the military said, a huge surge after years of relative quiet that followed a previous Israeli campaign to root out Gaza rocket launchers.

Israel had signaled that it would not launch a larger offensive if the militant group Hamas ceased the rocket fire. But the same time Prime Minister Benjamin Netanyahu has instructed the military to prepare options for every scenario.

Military spokesman Lt. Col. Peter Lerner said the current round of hostilities was being dictated by Hamas and Israel would continue its barrage so long as its citizens were under fire from Gaza.

"We don't expect it to be a short mission on our behalf," he said.

Rocket fire from Gaza had been reported Tuesday with more than 15 rockets fired toward southern Israel, including the cities of Ashdod and Ashkelon. The military said five of the projectiles were intercepted by the country's sophisticated defense system.

None of the 2,700 vacationers and crew aboard the AIDAdiva was harmed and the ship continued to Crete without delay.

Israel's defense minister announced a special state of emergency in the region Tuesday as summer camps and kindergartens were shut down and residents were encouraged to stay close to their homes.

The military said it had targeted four houses belonging to Hamas militants involved in launching rockets at Israel or other militant activity. There were no reported casualties in the strikes.

The military identified the men whose houses were targeted as Eiad Sakik, Abdullah Hshash, Samer Abu Daka, and Hassan Abdullah.

In addition, the military said it struck three militant compounds, 18 concealed rocket launchers, and other militant infrastructure sites. Most were targeted by airstrikes, and three were attacked from the sea. Later, it also took out a Hamas command center embedded within a civilian building.

Hamas has amassed about 10,000 rockets, including longer-range rockets that can reach "up to Tel Aviv and beyond," Lerner said, adding that the military was preparing for the possibility that Hamas would launch rockets toward Israel's heartland and its commercial and cultural hub.

Lerner said last month's kidnapping and killing of three Israeli teenagers in the West Bank was connected to the intensified rocket fire carried out by Hamas militants in Gaza. Israel blames Hamas for the teens' abduction and is conducting a manhunt for two Hamas-affiliated Palestinians in the West Bank it believes carried out the kidnapping and killing.

The Associated Press contributed to this report.