You want to be in support of the civilians getting mistreated in Gaza, in a peaceful protest denouncing the actions of the Israeli government, that's fine. It's a legitimate concern and reason to protest.
You want to join up with the "kill all the Jews" types, or the ones celebrating the butchery, rape, and hostage-taking... yeah fuck right off with that shit you terrorist-loving shitbags.
You can be in support of the Palestinian people and still condemn the actions of Hamas.
You can also condemn Hamas and also be against the policies enacted by the gov't of Israel.
Nobody should be cheering for the deaths of civilians in either side.