With Tuesday's attacks on key Hamas structures and an incident at sea, Israel's defense minister said it is waging an "all-out war" on Gaza as fighting entered its fourth day, CNN reported.
The airstrikes, which Israel says are aimed at stopping the firing of rockets from Gaza into southern Israel, have killed more than 375 Palestinians, most of them Hamas militants, Palestinian medical sources said Tuesday.
Israel bombed a Hamas government compound early Tuesday, leveling at least three structures, including the foreign ministry building, eyewitnesses and Hamas security sources told CNN.
More bombs continued to drop over Gaza through the morning.
In the Mediterranean Sea, an Israeli patrol boat struck a boat carrying medical volunteers and supplies to Gaza early Tuesday as it attempted to intercept the vessel, witnesses and Israeli officials said.
CNN correspondent Karl Penhaul was aboard the 60-foot, Gibraltar-registered Dignity when the contact occurred.
In a radio message, the Israelis accused the vessel of being involved in terrorist activity, its captain said.
The Dignity was carrying 16 passengers and crew who were trying to reach Gaza through an Israeli blockade of the territory.
It was "very severely rammed" by an Israeli patrol boat that had been pursuing the volunteer boat for about half an hour before the collision, and the crew said their vessel was struck intentionally, Penhaul said.
But Israeli Foreign Ministry spokesman Yigal Palmor called allegations that the vessel was rammed deliberately "absurd."
He said the boat was trying to outmaneuver the Israeli vessel when it was struck.
The incident occurred in international waters, about 140 km (90 miles) off Gaza.
The boat was carrying boxes of relief supplies, volunteers and journalists to Gaza, the Palestinian territory now subject to an intense Israeli bombing campaign.
Monday, Israel's defense minister said the nation was in an "all-out war" with Hamas, which rules Gaza.
"We have stretched our hand in peace many times to the Palestinian people. We have nothing against the people of Gaza," Defense Minister Ehud Barak told Israel's parliament.
"But this is an all-out war against Hamas and its branches."
China urged Israel on Monday to immediately stop military operations in the Gaza Strip, while calling for the Israelis and Hamas to work towards peace.
"The Chinese side is shocked and seriously concerned over the current military operations in Gaza that have caused a large number of deaths and injuries," Vice Premier Li Keqiang said in a statement.
"The Chinese side strongly calls on the concerned parties to immediately cease military operations and adopt realistic measures aimed at easing the tense situation in Gaza."
The White House on Monday called on Hamas to halt rocket fire against Israel, so calm can be restored in Gaza.
The situation has triggered protests in Iran, Greece, Britain and Lebanon, and the Iranian government declared a day of mourning for Palestinians in Gaza.
Iran's Supreme Leader Ayatollah Seyed Ali Khamenei urged the world's Muslim populations to unite against Israel's attacks on Hamas in Gaza.
U.N. Secretary-General Ban Ki-moon condemned Hamas for the rocket attacks, but also had strong words for Israel.
"While recognizing Israel's right to defend itself, I have also condemned the excessive use of force by Israel in Gaza," he said in a prepared statement.