Thanks a lot for all the responses! I will try to find the time to go to a police station soon and report the incident. Hopefully they'll look into it and have a talk with the guy.

Regarding where he came from, I really can't tell - he looked Arab of appearance, but wore casual clothes, not a traditional Qatari dress. I don't believe his behavior was a result of nationality, though, as these idiots are to be found everywhere (but perhaps in a slightly higher concentration here).