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.
At a news conference free of the antics seen at many pre-fight gatherings, he told BBC Radio 5 live: "Don't ask me what's on the stick. Only one person will know about it. If that person wants to put it on social media, then the world will know."
The pair will meet in front of an expected 90,000 fans, a post-war record for a UK boxing match.
Neither man has spoken negatively about their rival during the build-up, but Klitschko broke rank briefly on Thursday, saying Joshua is no more than a "puncher" while adding that he himself is "a boxer who can punch".
The Ukrainian added: "I am the winner, already before the event. Even if it is his home, I'm taking it as my event and my fight, my win."
Joshua, who has had 18 professional fights compared to Klitschko's 68, responded: "If I couldn't box I wouldn't be here. I may not be the best but what I do good, I do brilliantly. That's got me here.
"If he claims to be the better boxer so be it, but when I start punching you in your jaw, you best stand up to the power. This is just another stepping stone towards greatness."
Klitschko - who shouted "fake news" at one reporter when asked about a rumoured eye-socket injury - is bidding to regain two of the three major titles he lost to Tyson Fury in his last outing in 2015.
He admits being introduced as the challenger still feels "weird" but pointed to his experience, stating he had been involved in boxing for the 27 years Joshua has been alive.
Victory for the Ukrainian would see him become a three-time heavyweight champion, like his retired brother Vitali, who believes Joshua is complacent in his approach.
"I've never seen my brother so concentrated," said Vitali.
"I want to say that Joshua is a great fighter, great skills, but he has never been at such a high level. He looks relaxed, like it will be easy. It will not be.
"After I was told about the fight I studied Joshua and I was happy. He has the right style for Wladimir, a good opponent."
Joshua enters Saturday's fight with 18 knockout wins in his 18 matches, while Klitschko boasts a record of 64 wins - 53 by KO - and four defeats.