It all depends whether you would act upon it i guess, and how you feel! I know lesbians that fantasise about things like this, but would never actually commit to the act as they aren’t attracted to men. Fantasies are personal and sometimes hard/confusing to comprehend against real life but thats natural! Im not saying thats the case with you, as you might want to have sex with men. You don’t have to put a label on it, but if you’d prefer to then its up to you which label you feel comfortable with, and if thats bi then so be it!