No it's not racist. But it's stupid and hurtful.
Stupid because love is unpredictable and no one can tell the future.
Hurtful, because well... let some one tell you they "don't like you", or they "don't find you attractive" and tell us how you feel.
Honestly guys, don't dwell on the negatives. Instead of focusing on what you don't like, why not just say, "I prefer white females"?