The interview was recorded late Tuesday night and will air Saturday night after the network's replay of boxing's richest fight, which Mayweather won by decision last weekend in Las Vegas to stay undefeated.
Asked if he thought Pacquiao was hampered by the right shoulder injury that later required surgery, Mayweather tells Jim Gray, "Absolutely not."
"Excuses, excuses, excuses," he said later.
"He was fast," Mayweather insists in quotes released Thursday. "His left hand was fast. His right hand was fast and he was throwing them both fast and strong."
Using an expletive for emphasis, Mayweather adds that "I'm not going to buy into" it, "and I don't want the public to buy into" it.
"He lost," Mayweather said. "He knows he lost. I lost a lot of respect for him after all of this."
Mayweather acknowledges that he earlier texted ESPN's Stephen A. Smith to say he welcomed a rematch.
"Yeah, but I change my mind," Mayweather said. "At this particular time, no, because he's a sore loser and he's a coward. . If you lost, accept the loss and say, 'Mayweather, you were the better fighter.'"