The Tennessee Titans safety appealed against the punishment, which was for his second breach of the league's safety rules this season.
Head coach Mike Munchak told the Titans Tonight radio show: "I'm not sure what we can or can't say about all those things, but this is tough.
"I know the players are still learning how to best, especially at his position, I think safeties, DBs are the ones that are always on the line for questionable hits or having a couple of those throughout the course of a couple of years.
"I think Mike, especially, I think there's a lot of factors. We felt like he'd be able to play this Sunday, and they decided against it."
Rivera, who has 260 receiving yards and two touchdowns so far this season, has been limited in practice with a concussion since the incident.