Current Employer is not re-leave me after notice period?

Hi, I have a software employee of reputed MNC in India with 2.4 years experience. I have sign a company rules when I was joined in that time. I got another opportunity in some other company. I am interested to join in new company. In present company is not given permission to re-leave with 1 month notice period. As per the documents they are mentioned clearly notice period is one month. But, they are not permit to re-leave. They said we have project issue in our company you have to stay here we don't provide any re-leaving to you. In current observation there is not project is running now. I have not satisfied with the current job skills in present company. And another thing they permitted me to contract position to permanent in last 2 months back. In manager is not satisfied with my decision. He has asked why you re-leave with this company. We have project issue. I am not interested with this skill set in present company. I have sent a resignation mail to my manager to accept my resignation with one month notice period. And I have discussed with my HR. He said that you have confirm first with your manager then only I can re-leave you. manager is not accepting my resignation. Please tell me some advise for what to do for present employer is not accept my resignation. I ready to work with 1 month notice period also.