Actually, that is not true.
1. There is a terrorist organization bent on the destruction of the Jewish people and Israel in charge of the government in the Gaza Strip.
2. They have been nonstop launching misses into Isreal,
3. The missles are located in top of school buildings full of children and apartments full of people so Israel does not want to destroy those missles because it would kill innocent people.
4. Most importantly Israel did not attack at all and has killed no civilians. In fact they successfully carpet bombed tunnels where the Hamas leaders where hiding.