Can employer force me to serve notice period?

I joined 14 months ago and now I have received a new job opportunity which is One Time Opportunity. There are no dependencies on me as I have been released from the project by the manager and would be on Bench from next week. I checked them with the buyout and also personally had a discussion with HR, but My current employer is not willing to waive off notice period and forcing me to serve it. It is stated in my offer letter that: " During probation, your employment can be terminated with 30days notice or 'Basic Salary' in lieu of the notice period on either side. After completion of probationary period and confirmation of employment, if you voluntarily resign from the services of the company, you will be required to give 90 days advance written notice or 'Basic Salary' in lieu of notice period subject to the companies discretion. In the event of you having any incomplete work assignment, the company will have a discretion to relieve you only at the end of the 90 days notice period. Similarly, Company may terminate your employment by giving you 90 days notice or 'Basic Salary' in lieu of notice period." Can they force me to serve the notice period ? What would happen if I choose not to serve complete notice period and return all the company assets and start working with the future organization?