Top Congress leaders, including Mallikarjun Kharge and Sonia Gandhi, were in attendance.
The Congress has planned a nationwide "save democracy" movement to protest against the disqualification of Rahul Gandhi as the member of parliament, a day after a court convicted him of defamation for comments that many considered insulting to Prime Minister Narendra Modi. The decision was taken at a strategy meeting on Friday attended by top Congress leaders, including party chief Mallikarjun Kharge, former Congress president Sonia Gandhi and former Union Minister P Chidambaram.
"We discussed political strategy on Rahul Gandhi's disqualification. Abhishek Manu Singhvi briefed the members on the legal strategy. We have planned protests across the country in the coming days," said senior Congress leader Jairam Ramesh.
The party also welcomed the statement of support of all opposition leaders and called for "systematic" opposition unity.
Several Congress lawmakers and leaders of regional opposition parties - Mamata Banerjee, Arvind Kejriwal, MK Stalin, Uddhav Thackeray, KCR, Akhilesh Yadav - backed Mr Gandhi and attacked the ruling BJP government for its "dictatorship".
"The Congress welcomes the statement of support of all opposition leaders, we should now take the issue of opposition unity forward in a systematic way," Mr Ramesh said, adding, "The Congress president has been coordinating with opposition parties every day in parliament, now this has to be done outside also."
Besides Mr Kharge and Sonia Gandhi, Congress general secretaries Priyanka Gandhi Vadra, KC Venugopal, Jairam Ramesh, Rajiv Shukla and Tariq Anwar, senior leaders Anand Sharma, Ambika Soni, Mukul Wasnik, Salman Khurshid and Pawan Kumar Bansal, among others, were also present at the meeting.
Rahul Gandhi "stands disqualified from the membership of Lok Sabha from the date of his conviction", the lower house of parliament said in a notice on Friday.
"I am fighting for the voice of India and am ready to pay any price for it," he tweeted in Hindi, in his first reaction after the disqualification.
The 52-year-old was convicted and sentenced to prison for two years by a court in Surat on Thursday after he was found guilty of defamation in connection with a 2019 speech in which he referred to thieves as having the surname Modi.
His comments were seen as a slur against the Prime Minister, who went on to win the election in a landslide.
He is due to appeal against the verdict in a district court in Gujarat, also PM Modi's home state.
Members of the government and other BJP leaders said Mr Gandhi's remark was a smear against all those sharing the Modi surname.
"Rahul Gandhi is a habitual loose cannon and he thinks he can say anything without ever facing the consequences," information minister Anurag Thakur said. Ravi Shankar Prasad, a spokesman for the BJP, said the court had acted with "due judicial process".
On Friday, Congress lawmakers gathered outside the parliament to protest Mr Gandhi's conviction, Some party members also staged protests against his disqualification across the country.