Naveen dont worry, u can get married at Arya Samaj Mandir if both the spouse are Hindu.
make sure both the boy and the gal are competent to get married, hope you are 21+ and the girl is 18+
one additional thing ask your girl friend whether she is willing to enter this relationship or not, if she changes her stance after marriage then u may find some trouble.
after getting married in Mandir, get a certificate from the said Arya Samaj Mandir and get it regisetered.
u need not to go for court marriage kind of thing.
in case u find any physical threat from the parents of the girl after marriage then make a representation in this context to the local Police Authorities, they are duty bound to protect your life and liberty, in case of failure on the part of police you can approach the High Court concerned.
finally the advice is to take help of some local lawyer, for registration purpose you will need lawyer's help.