Mr Gandhi, who is facing criticism from the National Democratic Alliance for backing the terrorist's mercy plea, said he drew inspiration from Mahatma Gandhi and Babasaheb Ambedkar, who wanted to abolish the death penalty.
"In our country, we are living in times of division. A whole force which is dividing our country is in action mode and that spells danger," Mr Gandhi said.
Mr Gandhi filed his nomination today for the vice presidential election in the presence of former Prime Minister Manmohan Singh, Congress President Sonia Gandhi and Congress Vice President Rahul Gandhi. Others leaders who were present include Janata Dal United's Sharad Yadav, Communist Party of India (Marxist) leader Sitaram Yechury, Communist Party of India's D Raja, Nationalist Congress Party's Tariq Anwar and Praful Patel, National Conference's Farooq Abdullah and DMK's Kanimozhi.
The opposition's vice presidential candidate said he represents the people of the country and not any political party. "People's faith in politics itself has diminished and has collapsed. I would like to see a revival of that faith," he said after filing his papers.
The Shiv Sena, BJP's ally in Maharashtra, had criticised him for petitioning the President to save Memon. "Shiv Sena is doing its duty with dedication. What Shiv Sena has said, it had to. I feel that the death penalty and capital punishment belong to the medieval ages. Death penalty is wrong and this is my principle," Mr Gandhi said.
He said he has written a similar petition for Indian citizen Kulbhushan Jadhav, who is facing death sentence in Pakistan.
"As a common, independent citizen, it is my duty to fulfil my principles. I believe in that. I have drawn inspiration on death penalty from two persons - Mahatma Gandhi, who opposed it, and Babasaheb Ambedkar, who said it is only proper to abolish it," Mr Gandhi said.
The former West Bengal governor and grandson of Mahatma Gandhi and C Rajagopalachari has been picked by 18 opposition parties. The vice presidential election is on August 5. Mr Gandhi will contest against the National Democratic Alliance's candidate M Venkaiah Naidu.