Klitschko, who is entering his 29th world title fight, revealed on Thursday he has made a video of his prediction for their heavyweight bout at Wembley.
That has been saved on a memory stick which will be sewn into his robe.
"It's strategy," said Joshua, 27. "An attempt at a mind game. I didn't take it the way he wanted to express it."
Former heavyweight champion Klitschko, 41, will auction his robe - and its contents - for charity after the Wembley Stadium super fight for Joshua's IBF title and the vacant WBA belt.