No, you are right about the assassination. India Gandhi ordered the Indian military into the Golden Temple to expunge the Pakistan-supported militants who has holed themselves into the Sikh shrine. The man who lead this campaign to rid the temple of the militants was Sikh Indian military officer. Indira Gandhi’s body guard, a Sikh, assassinated her for ordering the military action which damaged the facade of the shrine.
The Golden Temple is the most important shrine to Sikhs.
She was murdered by 2 of her Sikh bodyguards...
...in retaliation for Operation Blue Star:
Wiki says that she was assassinated by her Sikh bodyguards.