My father refuses to let me marry a boy because of caste; is "caste" an important part of marriage?

I'm a Muslim girl and want to marry a Muslim boy who is following Islam properly. So I spoke with my guardian (الولي), that is my father, and he refused the proposal and does not want to meet his family because of difference in caste, as we are jatt and they are mirza. Is cast an important part in Nikkah?