Notice Period Mandatory

Below is the email from my Company at the time of promotion: On the basis of review of your recent performance and potential, the Management is glad to promote you as Project Lead. Further, in line with change in the organizational policy, your notice period has been amended to 90 days. Also, your notice period cannot be adjusted against leaves or any compensation / salary in lieu of. The decision of Management in this regard will be final and binding on you. You affirm that you shall abide by all the policies of the organization made applicable from time to time, and any such policy if creates an addendum in your employment terms the same shall be deemed as accepted by you". Now, I am getting better opportunity where my pay scale would be more than 10 Lakhs. I am ready to serve the notice period of 60 days but not possible to serve 90 days. Please advise.