Not racist although I think there's circumstances where it can be. If it's "I don't want to be with anyone of this race because I don't find them attractive" that's not racist. If it's "I won't go with anyone from this race because everyone from this race is a !@#% and I think they should all !@#$!" then yes that is racist.
But since science has shown that people are more inclined to be attracted to people who look similar to them, I think it most cases it's not racism at all.