My parents were born in Goa and were married in Goa and have settled in Pakistan. They were born in 1930 and 1931. They had to surrender their Portuguese passport in order to get the Pakistani passport. Can we children apply for the Portuguese passport?
What matters most is whether your parents were still considered Portuguese citizens at the time of your birth and apparently, that wasn't the case. Proving they come from Goa might have allowed your parents to reclaim Portuguese citizenship if they became Indian citizens in 1961 but
- it would not necessarily make you, their children, Portuguese citizens and
- it's not what happened, by your telling they renounced their Portuguese citizenship voluntarily to become Pakistani citizens.
Also I don't know Portugal's colonial history very well but not every resident in a European colony was a “citizen” as far as the laws of the colonial power were concerned (that distinction is a big part of what makes a colony a colony), that would also be something else to check.
There are multiple definitions of the word colony. It also means overseas territory governed by the central administration. Its is a group of your own people settled in another region. The law states all born in mainland Portugal and its overseas territories (Jus soli) and those who are descendants of a Portuguese parent or a Portuguese grandparent is legible by blood. (Jus sanguinis).
The world wanted to call the Portuguese overseas territories colonies. But the peoples of the colonies are never eligible for citizenship. Only 3 European countries had this in their law. The first is my Portugal and the others being the Netherlands and France. Although the eligibility for qualification of the other 2 may differ from Portugal.