Try living under an occupation first.
You can't justify taking the lives of civilians, occupation or not, at any point in time. It doesn't cause people to support the cause of the Palestinians by making themselves appear to be savages with little self control either.
It surprises me that more people don't recognize this and try to remind people in the midst of this that this is not the intention of the movement to oppose the occupation rather than making comments like this justifying these acts because of the occupation.
Everyone is being taken advantage of. My country is complaining about universal healthcare and giving billions of dollars to the Israeli government and there is nothing I can do about it. I would rather have better healthcare than support something like this, but that doesn't mean that something like this forces anyone to change their character and become hostile in response.
It would be better to respond in a way that would demonstrate that supporting the Palestinians is supporting a just cause. Comments like this do not make your cause any more just than the Zionists.