Typically certain races have certain features which are more common.
Most people aren't attracted to all types of people.
Being attracted to only people of certain races is normal, because if a given race has particular features you find attractive, while another race does not, you're going to have a preference to the race with.
It's only racist when you don't like someone just because of their race.
I don't find most black people attractive. Most of the 'black' people I do find attractive are more mixed race, and part of the result of that is non-black features are more prevalent (but they are still called black due to skin colour), so to me they are more attractive due to those features.