Are khamar comes under schedule caste?

No they don't. They are in general cast.
According to government Caste System Documents, " Khamar " comes in Vishnavs Verna of hindu religion.

Khamar are Vaishnavs from Gujarat. Generally they used to known as Vaishnav Khamar. Falls under General Category not in a reservation. its not well known because of their population approx 9800 all over the world.

Various misunderstandings about this caste but it certified by government that they are Vaishnav Khamar falls under general like Brahmins, Vaishnav Baniyas, Brahmbhatts, etc. Vaishnav Khamar is an another subcaste of vaishnavs like Vaishnav Baniyas.