Afridi said his former team-mate Abdul Razzaq had first talked about the involvement of some players with fixers during 2010 World T20.
In his latest autobiography titled "Game Changer", the former cricketer said his stance was motivated by "social and religious reasons".
Afridi also admitted some factual errors had appeared in the book which would be corrected in the second edition.
Akhtar also claimed that 10 senior players had later apologised to them.
The former Pakistan T20 skipper also offered to arrange visa for Gambhir's visit to Pakistan.
The former Pakistan all-rounder described the former captain Miandad as a small human being.
Cricket experts and fans have long questioned the purported ages of various Asian players and Afridi's revelation will only fuel the controversy.
Afridi in his just-released autobiography had referred to Gambhir as someone who has a "lot of attitude and no great records"
Afridi played 398 ODIs for Pakistan with a lot of matches as opener but the average despite 8000 plus runs stand at less than 24 compared to Gambhir close to 40.
The revelations in his autobiography means that Afridi was not 16 when he smashed a record-breaking 37-ball hundred against Sri Lanka in Nairobi in 1996.
Afridi's career has not been without its share of controversies, intrigues, scandals and top cricketing performances.
Chris Gayle, who recently announced that he will retire from ODI cricket after ICC World Cup 2019, now has 477 sixes to his name surpassing Afridi's international tally of 476 sixes.
Former Pakistani all-rounder Shahid Afridi backed their Prime Minister Imran Khan's claim that the country had no role in the suicide bombing that killed 40 CRPF soldiers.
The 16-year-old beat Sachin Tendulkar, Shahid Afridi to claim the record during the second ODI between Nepal and UAE.
Butt said he was close to being selected for the World T20 in India after he had resumed playing domestic cricket following the completion of his ban in 2015 but Afridi resisted his selection.