Yes, you can pursue Postgraduation in Computer Science after Graduation in Electronics , perhaps you need to Qualify GATE Examination in Computer Science. Followed by an Interview before getting admitted to some of the higher technical institutes in India, like Top IITs, NITs, IIITs, IIIT Hyderabad, BITS Pilani, DTU, IIIT Delhi, IISc Bangalore and so on. However certain IITs and IISc, clearly mention an eligibility of B.Tech/B.E. in Computer Science or IT for pursuing M.Tech in CSE, however it is rare, but you should refer brochures of respective institutes in detail.

For more information do follow the link below

https://engineering.careers360.com/colleges/list-of-me-mtech-in-computer-science-engineering-colleges-in-india