"The G-est thing Mike Tomlin ever did, he handed me an envelope after that," Harrison said on Barstool's "Going Deep" podcast. "I'm not going to say what, but he handed me an envelope after that."
Harrison initially was fined $75,000 for the hit -- the most, he said, that he was ever fined (the NFL later reduced it to $50,000). Massaquoi suffered a concussion as a result of the head-to-head hit, which was not flagged in the game.
"Listen, on everything I love, on my daddy's grave, I hit that man with about 50 percent of what I had, and I just hit him because I wanted him to let loose of the ball," Harrison said on the podcast. "If I had knew they was gonna fine me $75,000, I would have tried to kill him."
Harrison's fine also was high because he was considered a repeat offender, and he had been fined $5,000 earlier in the season for unnecessary roughness.
Steelers president Art Rooney II issued a statement later Thursday denying Harrison's claims.
"I am very certain nothing like this ever happened," Rooney said. "I have no idea why James would make a comment like this but there is simply no basis for believing anything like this."
Bill Parise, who is Harrison's advisor and former agent, told the Pittsburgh Tribune-Review on Thursday that it "never happened."
"Absolutely not," said Parise, who was unaware of Harrison's comments until contacted by the paper. "Never happened. I would have known that. It didn't happen. James and I are still together. We were really close during our 18 years. He would have said something along the way."
The NFL, which declined to comment when contacted by ESPN, previously dealt with coaches paying players for hits in the New Orleans Saints' "Bountygate" scandal, where coaches offered cash rewards to players for knocking opponents out of games.
Saints coach Sean Payton was asked about Harrison's comments Thursday during a radio interview on Baltimore's 105.7 The Fan and said people "shouldn't hold their breath" for the league to investigate.
"That'll be something that's tucked away or under the rug at Park Avenue," Payton said in reiterating his long-standing complaints about the way the NFL handled the Saints' bounty scandal. "They'll look into it briefly. ... Listen, don't get me started on that. I lost $6 million in salary. And honestly it was something that I'll never truly get over because I know how it was handled and how it was run and the reasons behind it. And that's just the truth."
Harrison's new comments echo the sentiments he expressed after the hit a decade ago.
"It was a legal hit," Harrison told the Pittsburgh Post-Gazette in 2010. According to the newspaper, Tomlin agreed.
ESPN's Mike Triplett contributed to this report.