WBA and IBF light-welterweight champion Khan recently targeted a Mayweather fight at Wembley in the near future.
However, the 24-year-old has responded furiously after Mayweather announced that he would rather take on WBC welterweight champion Victor Ortiz.
"I'm not a big enough draw to fight in 2012, and Victor Ortiz is now?" Khan told Boxingscene. "If Floyd wants to fight now, I would. He only talks down on fighters who are threats to him."
Although Ortiz defeated Andre Berto in his most recent contest, Khan has proved his ability to draw a significant American audience and Ortiz has appeared on his undercard twice.
Mayweather has made plans to make his long-awaited return to the ring on September 17.