The 42-year-old was hospitalised after falling unconscious and later transferred to a US hospital for treatment.
The actress's manager Subroto Ghosh told IANS: "Manisha underwent a surgery on Monday at around 9am. I got a message from her family members and they said it was a successful surgery.
"Manisha's mother, father and her brother are by her side. One of her close friends is also there with her," he added.
The Akele Hum Akele Tum star wrote on Twitter asking fans not to be sad for her in her present condition but to "celebrate life in all its forms".
Koirala found fame in the '90s with films such as 1942: A Love Story and Mani Ratnam's Bombay.
She recently made a comeback with Ram Gopal Varma's Bhoot Returns following her divorce .