Your vote on this answer has already been received
Whatever it may be...but the question is : What is stopping Indian government from taking tough action against Pak? only verbal protests will not be effective. The Indian government will have to do something efficacious which would constitute a befitting response. But India, on the other hand, is indecorously sensitive about internationalising its conflict with Pakistan. India has shied away from deploying even non-military options to discipline Pakistan. It should instead gather international support against Pakistan for its highly provocative and cowardly act.