The 22-year-old singers were good pals during their rise to fame but the Heart Attack hitmaker admits that while she wishes Miley good luck in her life, she cannot see them hanging out together again.
Speaking on The TJ Show on Boston's 103.3 AMP Radio, she said: "We're like ... we're acquaintances."
"It's life, and people change, and, you know, I don't have anything in common with her anymore, and I wish her all the best."
Despite admitting the pair are not pals, Demi recently insisted she had a much easier transition from a Disney star to a mainstream pop artist compared to her former friend because she checked into rehab for addiction issues and an eating disorder in 2012.
When asked why she didn't leave Disney and develop a raunchy image, she replied: "I guess my transition was a little easier because I went straight to rehab. I didn't twerk - I just went to rehab!"
"But you know what, I think the world needs to get over the fact that Miley was Hannah Montana when she was 16.
"Nobody knows her. Nobody really knows who I am, and the same with Selena Gomez and Jonas Brothers and everyone that has grown up in front of the public eye. We're adults now."
Demi admitted in 2012 that the pair used to have "brutal" fights because of their fiery personalities even when they were good friends, and she insisted at the time that she would always be pals with Miley and Selena Gomez.
"Both Miley and Selena will never leave my life no matter what happens, because we've been through so much together."