The statement that Israel has the right to defend itself against Palestine is similar to the statement that if, say, the US annexed, occupied, and started building illegal settlements in Cuba (the parts the US isn't already illegally occupying and using as a torture camp, Guantanamo), then the US would have the right to "defend" itself against Cubans acting in retaliation to US aggression.

Everyone aside from blind fundamentalists and/or the hopelessly corrupt would laugh at the notion that in such a situation, US action against resistant Cubans would be "defense".  Likewise, the world laughs at the idea that Israel can "defend" itself against the vastly more outgunned Palestinians resisting Israeli aggression.