The 43-year-old American star retired from boxing in 2017 with an unblemished record of 50 wins and no losses.
During an appearance on ESPN's SportsCenter -- when he was 49-0 at the time -- Mayweather listened as the two hosts picked their respective top five boxers of all time.
David Lloyd chose Henry Armstrong (fifth), Mayweather (fourth), Joe Louis (third), Sugar Ray Robinson (second) and Ali (first).
Meanwhile, Cari Champion selected Mike Tyson (fifth), Mayweather (fourth), Louis (third), Robinson (second) and Ali (first).
But that didn't stop Mayweather from launching a rant about the merits that led to Ali taking home the top spot.
"What are we judging fighters on?" he asked.
"Because if we're judging fighters on standing for a cause, then it's Ali hands down.
"But if we're talking about taking the least punishment and breaking records, it's Floyd Mayweather.
"Muhammad Ali paved the way for me to be where I'm at today, he's a legend.
"But when we talk about record breaking, we've got to talk about Ali losing his world title to a fighter with only seven fights.
"I have to take my hat off to Ali, but I didn't give this sport 40 years to say that there's another fighter better than me."
Lloyd argued that Ali's boxing resume included legendary fights like his Thrilla in Manila showdown with Joe Frazier.
And when the SportsCenter host suggested that Mayweather didn't have the same kind of brawls as Ali, he hit back: "That's not cool. That's not cool.
"What I'm here to teach fighters is this: the name of the game is to hit and not get hit. It's not about taking punishment.
"And I love Ali, but sitting on the ropes, taking punishment as far as doing a rope-a-dope -- that's not cool."
Mayweather, who last fought against UFC superstar Conor McGregor, has previously argued that he was better than Ali.
But boxing legend Tyson branded Mayweather as "delusional" for believing that he was superior to the 'Greatest.'