Last week, Ricciardi criticized Dunn on a Toronto radio station, accusing the slugger of lacking passion for the game.
"We've done our homework on guys like Adam Dunn and there's a reason why we don't want Adam Dunn," Ricciardi responded to a caller asking about trade rumors. "I don't want to get into specifics."
After reading a transcript of the remarks, Dunn shot back, calling Ricciardi a "clown sitting in the front office pushing paper."
Ricciardi later apologized and tried to contact Dunn through Reds GM Walt Jocketty.
Before the Reds played at Toronto Tuesday, Ricciardi said he had taken a call from Dunn on Saturday and apologized for starting the furor. Asked later about the call, Dunn denied it had taken place.
"If he said he talked to me, it's a lie," Dunn said.
Ricciardi believes he may have been the victim of a prank.
"I got a call from someone who identified himself as Adam Dunn," Ricciardi said. "It's extremely disappointing if that's not an accurate phone call. I apologized to the person on the phone."
Dunn went 1-for-3 with a double Tuesday as Toronto beat Cincinnati 14-1.