Mishra also attacked External Affairs Minister S M Krishna for not defending Home Secretary G K Pillai when Pakistan Foreign Minister Shah Mahmood Qureshi attacked him during their joint press conference in Islamabad on July 16.
The talks were "bound to fail" as there were elements in both India and Pakistan who were not very happy with the way talks had been arranged, he told Karan Thapar on CNBC.
"There have been problems both on our side and on the Pakistani side. It is now fairly well known that even the government was divided on the issue of undertaking talks with Pakistan without Pakistan having done anything on terrorism," he said.
Asked if it was a "serious mistake" on government's part to resume dialogue with Pakistan, Mishra said, "Most certainly it was. Pakistan has done literally nothing against those responsible for carrying out 26/11 Mumbai attacks."
He added that the government should not have held talks, particularly if it knew about the involvement of Pakistan's armed forces' personnel in the Mumbai attack.
"Where was the need to go and talk to the civilian authorities when you know that armed forces are not going to allow any kind of forward movement," asked Mishra who was NSA during the National Democratic Alliance government.
"Even within the Congress party, there have been differing voices" on holding talks with Pakistan, he said, noting that Pakistani armed forces wanted the tension between the two countries to continue while part of the civil establishment wanted to move forward.
He said unless Pakistan goes back to the commitment made by General Parvez Musharraf to then Prime Minister Atal Bihari Vajpayee that terrorism and dialogue can't go together, "There is no point in talking to Pakistan."
On Qureshi's attack on Pillai, Mishra said, "When the External Affairs Minister goes abroad, he is not representing himself, he is representing a billion people and if a billion people are going to be put in shame..it is your duty unless you had agreed with him in private."
He said he was "surprised" that Krishna did not contradict Qureshi.
Image: Brajesh Mishra
Can we move on from Pakistan, Mr Prime Minister?
Why it's time to be blunt with Pakistan
Never said Krishna was always on phone: Qureshi
National Security Adviser to visit China
Pakistan Army chief meets Gilani