Hi Kunal,
In New Facebook Graph API 2.0 ,Friend list is no longer part of the default permission set and has its own permission. The new permission is called user_friends that can be used in your case.
I think you are using Facebook v2, this will only return those users who have installed the Facebook app not your all Facebook friends.
Let me know if it helps.
Thanks and Regards,
// Naresh Dwivedi