Yes - if your parents won't accept that Asperger's syndrome is a real diagnosis at all, it probably won't be constructive to use the term. Perhaps you could start out by doing what others have suggested - explaining that you have some symptoms and you need to find some solutions for them.
(Of course, you are not necessarily looking for "solutions" - far be it from me to declare that you are - but if you pinpoint problems that are actually impacting something your parents care about, like academic progress, and state that you want to improve on that thing they care about, they may be friendlier toward the idea than if you just say you need to see someone. You've said that they're predisposed to thinking that people "just want attention," so it's best to have something concrete to which you can point, so that they don't assume you are just in it for attention.)
Following that, you may be able to discuss this particular problem with whatever professional you see - I mean, the fact that your parents don't accept the existence of the diagnosis. They may have their minds more effectively changed if someone with professional qualifications explains exactly what the diagnosis means, its strengths and weaknesses, and the ways in which you meet these purely academic (i.e., no value judgment) criteria for diagnosis.