Is there anything wrong with wanting same sex friends but not opposite sex friends?

Well, what if the only people I want for friends are other people who are exactly like me? And I don't WANT anyone's perspectives other than my own?

then you can stay in your bubble and create a couple of imaginary friends who will say and do whatever you will tell them to.. 

Well, is there any law that says you have to have opposite sex friends?

Well, why shouldn't I confine myself to one specific set of eyes? This means that the one set of eyes is the correct point of view ans perspective to have, and any other is quite obviously the incorrect set of eyes.

You've convinced me you're right.  Stick with people who only think your way.  You'll be much happier and so will the rest of us.

Well how do I make same sex friends while avoiding opposite sex friends?

I'm confused: I thought most of us learned how to make friends within the first five years of life. Not only that, the majority of our first friendships in life are same-sex. 

Why is this so difficult for you to grasp?
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Because I have Asperger's syndrome l, an autism spectrum disorde, and these things do not come naturally to me.

That would explain it. I'm sure that it's not obvious to others that you have it, especially not on a one-dimensional website screen.

If you attend therapy, do they suggest ways you can make friends?
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They do. Mostly groups with others on the spectrum.

I see. So you're most likely posting this question because whatever you've tried before isn't working at all, or or it used to but isn't working any more. Try something new, something different, something like this: for a moment, forget about the groups you already know about.  Think of two things you already love doing a whole lot, and two things you'd love to do but have never tried.  
The first two could be a hobby, a family-oriented activity, pets, animal-watching,  a sport, an internet-related thing, something you collect, cooking, eating a particular kind of food, your favorite beverage, work-related, reading, sight-seeing, a place you like to visit, a favorite video game, a TV program, a movie genre, a community event that helps others, chores, anything.
Then, instead of doing it by yourself or with people you already know, you're going to branch out to a different place, time and way to do it. If you do it at home, try it at someone else's home, at a park, a library, in the next city, the next county, etc. If you only do it on the weeknights, do it on a Saturday afternoon or a Sunday morning.  If it can't be done at night because of darkness, go to a well-lit place and do it anyway.  If it's usually done alone, invite one person to do it with you, and ask that person to also invite another person along. If it's something that costs a lot of money, try doing it some way that is free or nearly free. If it's already free, do it in a way that you have to spend some money. 
Next, try to find someone who has NEVER done your favorite thing(s) and become their teacher. Or, find people who teach it and become their assistant.  Find someone who barely speaks English or is learning English and offer to help by involving him/her in your favorite activity. 

Ahhh I am familiar with that.. I did wonder if there was a specific reason why you were wanting to avoid opposite sex.   Makes sense now.. 

How exactly does my having Asperger's cause it to make more sense?

LOL easy.. just talk to the preferred sex and not the other.. real, real, easy... I think we all naturally gravitate more to one sex.. so just don't cultivate or take up friendships with those of not the preferred sex... 

Personally I prefer men as friends..  worked very well for me.. I find we compliment each other and I have had some truly awesome male friends.. but if I only wanted women friends then that's easy too.. just don't put in the effort if they aren't someone you want to become friends with.. in your case because they are the wrong sex... in other's cases cos they aren't someone you like or want to be friends with..

I guess I'm thinking what if someone tries to introduce me to someone of the opposite sec and I want to avoid all contact.

well there is a world of difference between not having friends of the opposite sex and avoiding them..  we can all pick and choose who we are friends with.. and it's easy to avoid starting or building a friendship with someone you don't like.. but when it comes to avoiding all contact. .that would be difficult.. and would probably make difficulties for you too in your life..