Adds quotes, details (first version published at 12:28)
Israel will cease its attacks on Gaza if Palestinian militants stop firing rockets and mortar shells at southern Israeli communities, Defence Minister Ehud Barak said Sunday, dpa reported.
He spoke amid the worst cycle of violence in Gaza and southern Israel in two years.
The violence has flared since a mortar shell fired from Gaza Thursday afternoon hit an Israeli school bus and critically wounded a 16-year-old boy.
Since then, Israel has struck 11 groups of militants it said were involved in the rocket and mortar fire, and bombarded another 15 targets linked to militant factions, including Hamas, the Islamist movement ruling the Strip.
Palestinian groups have since Thursday fired at least 130 rockets and mortar shells at southern Israel, including at least 10 Russian- type Grad missiles, a military spokeswoman in Tel Aviv said.
Since Thursday afternoon, at least 18 Palestinians have been killed and 66 wounded - about one third of them civilian men, women and children - in the intense Israeli airstrikes.
Israel carried out no new airstrikes during the night and early Sunday, the spokeswoman said, but four more projectiles landed in the southern Israeli Eshkol region, with one of them hitting an electricity line and causing power blackouts.
Israel's newly deployed Iron Dome short-range missile defence system had shot down eight of the missiles since Thursday, protecting mainly the larger southern Israeli cities of Beersheba and Ashkelon, the spokeswoman told the German Press Agency dpa.
There is no "bang-and-it's-over" solution against the rocket and mortar fire, Barak told Israel Radio. The defence minister said Israel would carry out a second Operation Cast Lead only if this was "necessary."
Residents in southern Israel and in Gaza, however, said they felt an atmosphere similar to the escalation that preceded Operation Cast Lead, the Israeli offensive in the winter of 2008-2009. The offensive, aimed at curbing the rocket and mortar fire from Gaza, killed about 1,400 Palestinians in three weeks.
Commenting on the school bus that was hit, Barak said: "We considered that something that we cannot accept and it is a must that we respond with all the force."
Abu Obeida, the spokesman of Hamas' armed wing, told a news conference in Gaza City late Saturday afternoon the Islamist group would discuss no ceasefire with "the occupation (Israel) while our people are bombarded and massacres are committed against them."
He said Hamas was claiming responsibility for 68 of the Grad missiles, rockets and mortar shells fired at southern Israel, including the mortar targeting the Israeli school bus Thursday.
The barrage was revenge, among others, for the killing of three Hamas militants in a targeted Israeli airstrike on their car in southern Gaza on April 3.
"We are keeping our response for the appropriate time," Abu Obeida said at the time.
Israel said the three had been planning to abduct Israelis vacationing in the Sinai peninsula of Egypt during the upcoming Jewish Pesah (Passover) holiday.
Howver, Hamas' political leadership and its de facto prime minister in Gaza, Ismail Haniya, wary of losing their hold of Gaza in case of a second major Israeli offensive, seeks a restoration of the relative calm of the past months.