Why would you be surprised Israel's persecution of the Palestinians would be a recruiting tool ? It's a major issue for almost every Muslim worldwide. ISIS have absolutely been recruiting on the back of this and I've seen recruits from Australia even mention it when interviewed.
There are plenty of examples:
http://www.businessinsider.com.au/the-manual-al-qaeda-and-no...
http://www.cbsnews.com/videos/king-of-jordan-isis-used-gaza-...