People need some quick help i kept it short?

ok so im an 18 year old guy and i have a female friend. i noticed that i have had thoughts of doing things that friends dont exactly do. i dont wanna date her and i dont feel that way about her but im starting to think of her in a more sexual way. she doesnt know about this and all she knows is that i think shes cute and i flirt sometimes but i in no way wanna be more then friends and wont sleep with her since im not inlove with her. is this normal? do you guys ever have like sexual attractions tto friends of opposite genders? i dont have alot of experience with female friends so will this hurt the friendship later on?