Surprisingly a lot of people don't know about it. Here's some info.
It’s worth noting that Dwayne “The Rock” Johnson and Shawn Michaels, who long harbored animosity towards each other, crossed paths during WrestleMania weekend. WWE.com published a photo of Johnson and Michaels sharing a laugh shortly after HBK had appeared on stage at WrestleMania XXVII to commemorate his induction into the WWE Hall of Fame. According to F4WOnline.com, their past animosity was actually settled in 2008 when Johnson inducted his father, Rocky Johnson, and grandfather, High Chief Peter Maivia, into the WWE Hall of Fame.
Johnson’s issues with Michaels dated back to when he was a teenager. He long harbored animosity towards Michaels because he felt he was disrespectful to his maternal grandmother (Lia Maivia) at a wrestling show she was coordinating for Polynesian Pacific Pro Wrestling. His disrespect towards her incensed Johnson, and nearly led to an altercation.
Their issues persisted several years later when Johnson was a rookie starting out in WWE. Bret Hart wrote in his 2007 autobiography, Hitman: My Real Life in the Cartoon World of Wrestling, that Michaels and Triple H disliked Johnson “intensely.” Both resented him because he was talented and Hart, a political foe, had taken a shine to him. Many believe they were out to sabotage Johnson so that Hunter would ascend to the top before him, since they were both viewed as the future of the company at the time.
Michaels and Hunter conspired to obstruct Johnson’s push in March 1997, who was the Intercontinental Champion at the time. Michaels suggested to Vince McMahon that Johnson lose the title to Hart on an episode of Raw. Meanwhile, Hunter insisted to Hart that he beat Johnson. Their suggestion would serve two purposes — sabotage Johnson’s push and take Hart out of the world title scene. Hart, however, refused to beat Johnson. Hart felt it wouldn’t build heat for his newly launched heel turn, not to mention that it would undermine Johnson. Instead, Hart insisted on a DQ finish, which infuriated Michaels and Hunter.
By 1999, Johnson had ascended to the top of WWE, going beyond nearly wrestler, including Hunter. Meanwhile, a back injury had forced Michaels to retire and he was relegated to sporadic appearances. Nonetheless, Michaels attempted to politically undermine Johnson by lobbying to McMahon that he be replaced by Hunter in the main event at WrestleMania XV.
Johnson stated years later in a 2005 interview with WWE.com that he never had interest in working with Michaels — when asked if he would have liked to.
Here's what The Rock said about HBK in an interview.
Keller: I don't think Shawn Michaels's name has come up other than when we talked about the Survivor Series. What are your thoughts on him? Was he helpful to you? Was he a hindrance to you? Was he someone you learned from, even his mistakes? Did he set a good example?
Rock: He was not helpful to me. I never sought his help. I really have nothing to say about Shawn.
Keller: Is that because if you can't say something good, you don't want to say anything at all?
Rock: Not necessarily. He was cordial with me as I was with him. But other than that, he doesn't know me well enough to speak of me and I don't know him well enough to speak of him.
Keller: Michaels is regarded as a fabulous athlete, a fabulous performer, and one of the best of this era or generation. If you agree with that to any degree, do you have a desire to work a top program with him if he were able to come back and work a handful of matches?
Rock: No, I have no desire to work with Shawn. None whatsoever.
Keller: Do you disagree that he was a great performer?
Rock: Not at all. He was a tremendous performer, a tremendous athlete. His work was an asset to the business.
I always wondered why these two never wrestled each other. It's one of the few dream matches we never saw. I do admire Dwayne for not putting HBK down. He had every reason to do so. Damn, HBK and HHH were some real pricks backstage.
They've always got along the few times I've seen them together though.