Ezra Nawi, 60, an Israeli citizen and pro-Palestinian campaigner, insisted the Norris bid for the Áras was deliberately sabotaged.
Mr Norris withdrew from the race after it emerged he had written to Israeli judges in 1997 pleading for clemency for Nawi after he had been convicted of the statutory rape of a 15-year -old.
Nawi said the information had been leaked in order to scupper the presidential chances of Mr Norris, who has been an outspoken critic of Israel in the past.
“It’s a very juicy story; I think some Israeli officials, embassy or somebody else, was involved in this, no doubt about it. Of course they will deny this,” he told RTÉ.
Nawi claimed that he had paid his debt to society and it was wrong to bring it into the presidential campaign, but he accepted he had done wrong.
Speaking about the 15- year-old victim, Nawi said: “We found ourselves together — he was the guy who phoned me but he was under age, no doubt about it.
“It happened and I paid my debt to society, I was in jail for three months. I’m not trying to justify this.”
Nawi said he understood why the revelation did so much harm to the Norris campaign.
“It doesn’t look good that a person involved in politics tried to help me — it doesn’t look well,” he said.
Nawi, 60, said Israeli authorities have used the conviction against him and his human rights campaigns, but he could not have imagined it being used against Senator Norris.
Nawi insisted the exit of Senator Norris from the race for the Áras was a loss to the Irish people.
The Israeli embassy in Dublin has denied the country had any involvement in the leaking of the Norris letters pleading for clemency.
Mr Norris said he stands over his letter of clemency but regretted not expressing enough concern about the 15-year-old victim in the past.