بسم الله الرحمن الرحيم
(Fatwa: 161/122/L=02/1435)
If your parents are not ready to get you married with that girl, then you should obey your parents and do not go ahead with nikah without their permission. There is no good in marrying without the consent of parents. However, marrying in other caste is lawful as per the Shariah, provided you do not abandon your parents.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
