Genocide is intent to destroy, in whole or in part, a national, ethnic, political or religious group by killing members of the group and/or deliberately inflicting on the group conditions of life, calculated to bring about its destruction. A massacre can be defined as the indiscriminate slaughter of people.
Israel is, at least, partly responsible for some massacres:
• Qana, 1996: Israeli artillery struck the Unifil Headquarters in Qana which was providing shelter to more than 800 Lebanese civilians. 106 were killed and around 116 injured. Hezbollah fighters had fired Katyusha rockets and mortars from the site, and the IDF responded with shelling. Greater care should have been taken to secure that no civilians was in the area, but Hezbollah must also be blamed for violating the rules of war.
• Qana, 2006: An estimated 28 Lebanese civilians were killed when the Israeli Air Force dropped two bombs on their shelter. Jihadist gunmen had used the shelter to launch rockets from the roof, and thus it was deemed a military target by the IDF.
• September 1982: Refugees are killed by the Christian Lebanese Forces militia in refugee camps surrounded by Israel Defense Forces. This was an act of massacre that Israel was at least indirectly responsible for.
• The battle of Jenin: An estimated 55 Palestinians died, 22 of them civilians according to Human Rights Watch, and some of these deaths constituted war crimes. The refugee camp was targeted after Israel determined that it had served as a launch site for terrorist attacks against Israeli civilians, which all of them constitutes war crimes. Actually, many military experts consider the battle of Jenin a model of how to conduct urban warfare against terrorists hiding among civilians because the number of civilian deaths was low compared to similar cases, such as in the Second Chechen War.
The enemies of Israel are responsible for at least 5 massacres on civilians:
• May 30, 1972: Three members of the Japanese Red Army, on behalf of the Popular Front for the Liberation of Palestine, killed 26 people and injured 80 others at Tel Aviv's Lod airport (now Ben Gurion International Airport).
• May 15, 1974: Members of the Democratic Front for the Liberation of Palestine shoot and kill a Christian Arab woman and a Jewish couple and their 4 year old son, and then take hostage and kill 22 high school students and three of their adult escorts.
• March 11, 1978: Palestinian Fatah members based in Lebanon land on a beach north of Tel Aviv, kill an American photographer, and hijack an inter-city bus driving along Israel's Coastal Highway. 35 civilians are killed and 80 wounded.
• January 22, 1995: First suicide attack by Palestinian Islamic Jihad, killing 22 and wounding 69. Carried out by two bombers; the second waited until emergency crews arrived to assist the wounded and dying before detonating his bomb.
• March 27, 2002: Killing of 30 guests at the Park Hotel in Netanya, Israel, sitting down to the traditional Passover Seder meal. Another 143 were injured. Hamas claimed responsibility.
From September 2000 to March 2003, approximately 20 % of the nearly 2,000 Palestinians killed by Israeli forces were civilians. This is a low ratio, compared to other similar conflicts, and thus proof that Israel is not deliberately targeting civilians. If they had, they must be totally incompetent, because the IDF would have no problem committing genocide due to its military capacity.
Actually, few other nations in a comparable situation have been more protective of enemy civilians. The ethical code of the Israeli army was compiled with the assistance of some of the country's leading moral philosophers. It commands every soldier to avoid causing harm to civilians.
On the other side, militant jihadists have expressed a desire to kill civilian Israelis; Israel has never expressed a desire to kill civilian Palestinians. Palestinian fighters have often engaged in terrorism, and several groups, such as Hamas, glorify the killing of innocent civilians. These groups have had support from several Arab nations, both financial and ideological. During the 1948-war, the expressed goal of the Arab armies was to commit genocide, and during the 1967 war, the armies of Egypt, Syria, Jordan and Iraq targeted Israeli civilians.
Of course, Israel often make mistakes and overreacts, and is justly criticized when they do wrong, but its overall record is still among the best in the world.