Diouf was tackled in the build-up to West Ham's first goal as the visitors came from two goals down to rescue a point at the Britannia Stadium, but referee Chris Foy allowed Stoke an advantage which turned out to cost them.
After the game, Hughes told BBC Sport: "It was dangerous play. It was reckless. We're grateful that Diouf jumped out of the way, because it could have been a nasty collision.
"The referee should come down on challenges like that - he needed to stop play, but apparently he was trying to play an advantage, which we didn't get. But it's not the first time we've been disappointed by a referee this season.
"I think everybody at the game knows who were the better side, and who created the most chances. Unfortunately, sport doesn't always give the spoils to the team who deserve it."
The result leaves Stoke 12th in the Premier League table, while West Ham slip to fifth.