If you have a negative attitude towards someone based on race or ethnicity rather than personal experience, you might be accused of prejudice.
Prejudice is remarkably similar to its Latin root in form and meaning; the Latin praejudicium means "judgment in advance." A racial prejudice is a negative attitude towards a group of people based on race — not on direct knowledge or experience. If you prejudice someone, you cause them to have a negative attitude towards someone else. Lawyers are not allowed to bring certain types of evidence such as rumors into a trial because it might prejudice the jury.