The U.S. intelligence agency orchestrated the story that the eastern European country's regime was behind the shooting, two journalists suggest.
Their new book says the attempted killing was in fact masterminded by an extreme-right wing Turkish group called the Grey Wolves purely because of their anti-western ideology.
Pope John Paul II was shot four times by a sniper in St Peter's Square, Vatican City on May 13, 1981. Mehmet Ali Agca, 23, was arrested and jailed following the failed assassination attempt. The Pope's life was saved after he underwent five hours of surgery. The gunman, using a 9mm weapon, had hit him twice in the stomach, in the arm and in his little finger.
But the new book - Kill The Pope: The Truth about the Assassination Attempt on John Paul II - claims Agca, a Turk, had no links to the Soviet cause. It has become widely accepted that Bulgaria was responsible for the shooting - although journalists Marco Ansaldo and Yasemin Taskin now say the theory is completely untrue.
The pair say former security service adviser Michael Ledeen was the original source for the story that Bulgaria was to blame.
Mr Ansaldo told the Daily Telegraph: 'There is no evidence that Bulgaria had anything to do with the attack on the Pope. The Bulgarian connection is the creation of the CIA.' The author said that Alexander Haig - who was Secretary of State - wanted material to use against the Communists as the Cold War raged.
The Grey Wolves had close ties with Bulgarian organised crime and the CIA were able to exploit them, he says. Mr Ansaldo added: 'The CIA knew the Grey Wolves had connections with Bulgaria through organised crime and that Agca had visited so when he tried to kill the Pope they were very smart and exploited the connection. The author also claims that Agca was forced to falsely confess to Bulgarian involvement.
The book comes after former Polish communist leader General Wojciech Jaruzelski said he thought 'radical Islamists' were responsible for the assassination bid in St Peter's Square. Judge Ferdinando Impostimato - who investigated the 1981 failed assassination - yesterday said the new book was 'rubbish'.
In the years before Communism collapsed, the Polish-born leader of the Catholic church had ignited opposition in his homeland.
The judge insists that the foiled assassination was an attempt to silence him.
Pope John Paul II collapsed following the shooting and was rushed to hospital - as the crowd in St Peter's Square reacted in shock.
Agca was eventually released in 2000 after serving 19 years when he was pardoned by the Italians - with the consent of the Pope.
John Paul II died in April 2005.
An official inquiry into the shooting blamed Soviet-sponsored assassins who wanted the pope dead because of his support for the democracy movement Solidarity.
General Wojciech Jaruzelski - who has been diagnosed with terminal cancer - claims Islamic fanatics sponsored the would-be assassination.
'Radical Islam detested the pope and saw in him a leader of crusades,' he told Poland's 'Jezus' Catholic magazine.