Mayweather says the league was influenced after seeing a second video of Rice knocking out his then-fiancée Janay Palmer in an Atlantic City casino elevator in February.
On Wednesday, Mayweather apologized for his comments, telling TMZ.com, "If I offended anyone, I apologize.
"I was just getting word from people that there was a video out there. I didn't know because I'm training for a fight," he said. "I'm not perfect, I make mistakes and I don't condone that at all."
The Ravens terminated Rice's contract on Monday and the NFL suspended him indefinitely.
"I think there's a lot worse things that go on in other people's households, also," Mayweather had originally said, according to the Associated Press. "It's just not caught on video, if that's safe to say."
Mayweather spent two months in jail in 2012 after pleading guilty to misdemeanor battery charges after prosecutors said he attacked an ex-girlfriend while their children watched.
Mayweather, who was speaking Tuesday at the MGM Grand in Las Vegas ahead of his rematch against Marcos Maidana, says he has been falsely accused in the past.
"Like I've said in the past, no bumps, no bruises, no nothing," Mayweather said. "With O.J. and Nicole, you seen pictures. With Chris Brown and Rihanna, you seen pictures. With (Chad) Ochocinco and Evelyn, you seen pictures. You guys have yet to see any pictures of a battered woman, a woman who says she was kicked and beaten (by Mayweather). So I just live my life and try to stay positive, and try to become a better person each and every day."
Mayweather (46-0, 26 KOs) will fight Maidana (35–4, 31 KOs) on Saturday.
- Scooby Axson