Delhi BJP leader Rajeev Babbar filed the complaint against Tharoor's alleged "scorpion" remark against Prime Minister Narendra Modi and said his religious sentiments were hurt by the statement.
Tharoor had stoked a fresh controversy Sunday while speaking at Bangalore Literature Festival, claiming that an unnamed RSS leader had compared Modi to "a scorpion sitting on a Shivling".
The complaint, filed through advocate Neeraj, termed the statement as an "intolerable abuse" and "absolute vilification" of the faith of millions of people.
Reacting to it, Tharoor told reporters, "The charges are frivolous ... If we start to stifle the right of the people to quote published material then where would our democracy head?... Where is the freedom of expression?"
Asked whether he felt the criminal defamation suit against him "is an attempt to throttle his voice", Tharoor said, "Apparently it seems so".
The complaint was filed under sections 499 and 500 of the Indian Penal Code relating to defamation.
The matter is likely to come up for hearing Saturday.