I believe that the Pakistani authorities were provided with the recordings of the calls between the terrorists and their handlers. They were also provided with confessions from the captured terrorist as well as other evidence they could get their hands on.
The operations were planned in Pakistan, the alleged training happened in Pakistan, the trainers, the planners the handlers were all in Pakistan. India doesn't have access to these places or to Pakistani nationals in Pakistan. It was the responsibility of the Pakistani authorities to gather further information against these people who have committed these acts but it seems they have been unwilling to act against them. Many people think that the Pakistanis don't act against them because these guys are supported by the Pakistani establishment.