JOIN USThey said that two women and seven children were among those hurt in the strike carried out late yesterday and this morning.
An Israeli military spokesman said aircraft attacked a total of six targets.
"They were two terror tunnels, two arms manufacturing facilities and two other sites," a spokesman told AFP, adding that the tunnels were intended for staging attacks under the border fence into Israel.
He said that the raids were in response to a wave of 56 rocket and mortar attacks from Gaza into Israel since Saturday.
Another tunnel was hit in a single and separate attack early Monday evening, the military said.
Palestinian witnesses said that among targets in the north and centre of the strip were a police post of Hamas, which rules Gaza, and a training facility of its military wing, the Ezzedine al-Qassam Brigades which earlier offered to stop cross-border fire into Israel if the Israelis halted attacks on Gaza.
A factory producing construction materials and a metal workshop were also hit, while in southern Gaza there were at least three strikes in the vicinity of Khan Younis town, witnesses said.
One targeted a group of fleeing activists, one a building belonging to the town council and another an empty plot, they said, adding that no casualties were recorded.
Gaza residents reported receiving telephone calls from the Israeli military urging them to leave the vicinity of Hamas facilities.
Ezzedine al-Qassam, which lobbed about 50 mortar rounds into Israel on Saturday, made its truce offer in a statement released after Israeli aircraft made their first raid on the enclave yesterday evening.
It said Saturday's barrage had been in response to an Israeli strike last week which killed two of its members, but that it was ready to call an end to the tit-for-tat violence if Israel also did so.
"If the enemy stops the escalation and aggression against our people we will implement the Palestinian national agreement," the statement said, referring to a truce reaffirmed by the main militant factions in January.