Here's what I answer when this question comes up:
Every single day for the last several months, the Hamas terrorists (they are the government in Gaza) have been firing missiles and bombs into Israel, targeting civilians. About a week ago, Israel had had enough and struck back, hard.
Historically ... in 1947 the United Nations said "There shall be two nations here, one Jewish and one Palestinian." The Jews said yes, and the Arabs said "Death to the Jews!"
For the past sixty years, the terrible Muslim leaders, Muslim dictatorships all around the Middle East, have kept the Palestinians as miserable pawns, hoping the Muslim people would hate Israel instead of hating the terrible Muslim dictators.