Floyd Mayweather says he never said he had sex with T.I.'s wife Tiny ... and claims the audio in the footage we posted this morning wasn't clear.
Mayweather tells TMZ Sports ...he ACTUALLY said, "he thinks I was f***ing his bitch."
In the video, Floyd does try to mutter something before the sex line -- but it's hard to make out.
Mayweather adds, "I've never been with Tiny sexually. I respect her situation and I think she's a good person. I would never disrespect a marriage."
T.I.'s wife Tiny confirms that statement ... telling us she's never had sexual relations with Floyd -- and thinks he only spoke out at the presser to get revenge for her BET Awards diss.
As for T.I. ... he simply told us, "I hope he is enjoying himself. God bless him."