The Geneva Conventions often get brought up in the discussions of what Israel is doing in Gaza or Lebanon, so I think it's worth looking at them in detail so we know what we're talking about. Here are the relevant bits, from the fourth convention:
Art. 48. Basic rule
In order to ensure respect for and protection of the civilian population and civilian objects, the Parties to the conflict shall at all times distinguish between the civilian population and combatants and between civilian objects and military objectives and accordingly shall direct their operations only against military objectives.
Art. 52. General Protection of civilian objects
1. Civilian objects shall not be the object of attack or of reprisals. Civilian objects are all objects which are not military objectives as defined in paragraph 2.
2. Attacks shall be limited strictly to military objectives. In so far as objects are concerned, military objectives are limited to those objects which by their nature, location, purpose or use make an effective contribution to military action and whose total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage.
3. In case of doubt whether an object which is normally dedicated to civilian purposes, such as a place of worship, a house or other dwelling or a school, is being used to make an effective contribution to military action, it shall be presumed not to be so used.
Art. 54. Protection of objects indispensable to the survival of the civilian population
1. Starvation of civilians as a method of warfare is prohibited.
2. It is prohibited to attack, destroy, remove or render useless objects indispensable to the survival of the civilian population, such as food-stuffs, agricultural areas for the production of foodstuffs, crops, livestock, drinking water installations and supplies and irrigation works, for the specific purpose of denying them for their sustenance value to the civilian population or to the adverse Party, whatever the motive, whether in order to starve out civilians, to cause them to move away, or for any other motive.
Art. 59. Non-defended localitiesIsrael ratified in 1951. Helena Cobban has made some good arguments on the need for a single set of standards, under international law, to resolve the conflict. I should stress again that, no matter whether you are "pro-Arab" or "pro-Israeli" the underlying issue here is that Israel is using collective punishment and targeting civilians who have nothing to do with Hizbullah. This humanitarian issue needs to trump all other considerations.
1. It is prohibited for the Parties to the conflict to attack, by any means whatsoever, non-defended localities. 2. The appropriate authorities of a Party to the conflict may declare as a non-defended locality any inhabited place near or in a zone where armed forces are in contact which is open for occupation by an adverse Party. Such a locality shall fulfil the following conditions: (a) all combatants, as well as mobile weapons and mobile military equipment must have been evacuated; (b) no hostile use shall be made of fixed military installations or establishments; (c) no acts of hostility shall be committed by the authorities or by the population; and (d) no activities in support of military operations shall be undertaken.