"Indian nation could not be cowed down by such blatant acts of deceit," party chief Sonia Gandhi said and urged the government to take up appropriate measures.
Vice President Rahul Gandhi also urged the government for "steps" to be taken "at the highest level", Congress spokesperson Bhakta Charan Das told reporters at the party briefing.
Das, however, rejected BJP's criticism of "weak" handling of the issue by the government.
Das, however, refused to comment on questions on whether after this incident, India will cancel its likely meeting with Pakistani Prime Minister Nawaz Sharif at the UN in September.
"India and the neighbourhood have made progress in the economic field. Whether talks should go on or not... On talks, I will not comment. Government has taken up the matter on diplomatic channels. This is not time to speak on that. An incident had happened and Congress President and Vice President have expressed deep concern on that," he said.
