Anthony Joshua has wished Jarrell Miller “good luck” following his failed drugs test – but said the American “doesn’t deserve to be in the ring with me or any other heavyweight right now”.
World heavyweight champion Joshua was due to fight Miller on 1 June in New York – the British fighter’s US debut.
But Miller was denied a licence after an “adverse finding” from a sample taken on 20 March.
“Karma works in various ways,” said Joshua, 29.
Speaking on his YouTube channel, he added: “What goes around will come back around and I feel like he has taken fate and his own blessings out of his own hands.
“I know it’s a fight, but be respectful, be appreciative, and lead by example. What he has done is not leading by example.
“Cheats will get found out, and hustlers and hard workers will always rise to the top.”
Joshua was due to to defend his IBF, WBA and WBO heavyweight belts at Madison Square Garden against the undefeated Miller, who has never fought for a world title.
At a news conference in February, Miller had called Joshua a “fraud” but the Briton said he did not rise to the provocation because he had to “lead by example”.
“I didn’t want to talk too much about the situation with Jarrell Miller because it is not in my character to knock a man when he is down,” Joshua said.
“However, there have been a lot of things he has said previously in the press conferences and build-up so I wanted to crack him in his jaw.
“But I know when you are in a position, you have to lead by example and I knew that wasn’t the right thing to do.”
A new opponent for Joshua is expected to be announced this week, with his promoter Eddie Hearn having said the boxer’s “preparations continue”.
“Whoever that fighter may be, I’m going to keep my chin down and hands up,” Joshua said.