"Sitting here today, dealing with all this stuff again, knowing if I were to go back, there's no way I could get a fair shake - on the roadside, in doping control, or the labs," Armstrong said on a late-afternoon conference call.
"I think it's better that way," he added a moment later. "I'm happy with the way my career went and ended and I'm not coming back."
The seven-time Tour de France champion and his handlers spent most of the remaining 45 minutes with reporters criticizing World Anti-Doping Agency chief Dick Pound.
It was Pound who set off another round of charges and counter-charges earlier Thursday by accusing cycling union boss Hein Verbruggen of supplying documents used by a French newspaper to charge that Armstrong used the blood-boosting drug EPO during his first tour win in 1999.
Armstrong, who has repeatedly denied ever using banned drugs, said he was the victim of a "witch hunt" after the report came out last month in L'Equipe, France's leading sports daily.
Armstrong said he was concerned Pound might be seeking revenge for an open letter he sent to newspapers and the WADA chief several years ago, defending his sport against the widely held notion that cycling was rife with performance-enhancing drugs.
"I was not trying to say that Dick was bad guy or a crook," Armstrong said of his letter, "but I might want to say that today. ... He's trying to divert attention from the serious ethical issues involving WADA and himself."
If true, that would violate WADA's own protocol requiring that any tests be done strictly for purposes of research.
Calls seeking comment from Pound at both his WADA office and home in Montreal were not immediately returned Thursday.
Earlier Thursday, Pound said he received a letter from Verbruggen acknowledging that the cycling union, Union Cycliste Internationale (UCI), had provided L'Equipe's reporter with forms indicating Armstrong had doped during his first Tour victory.
"Mr. Verbruggen told us that he showed all the forms of Mr. Armstrong to L'Equipe and that he even gave the journalist a copy of one of the documents," Pound said during a conference call from Montreal.
"I don't understand why they're not stepping up to that and saying, 'Well, I guess we do know how the name got public, we made it possible,"' he said.
But Armstrong said that he himself had authorized releasing the forms to L'Equipe. He said the request from the newspaper was to check whether the UCI had granted him any medical exemptions during competition, not to find out if the numerical code used by race official to identify Armstrong matched the one attached to the frozen samples.
Last Friday, the UCI said it had not received enough information to make a judgment on the doping accusations.
It also criticized L'Equipe for targeting Armstrong and Pound for making public statements on the "likely guilt of the athlete" without knowing all the facts.