"They're nothing bad!" Cyrus told Z100 New York on Friday, right before her sold-out Best of Both Worlds concert at Nassau Coliseum.

"At first, I was really upset. It really sucks," said the Hannah Montana star, who at one point exclaimed, "Look at me getting all upset!"

"It's not something I'm going to let slide," she said. "I'm really upset about it, 'cause it was, like, not even a big deal."

Cyrus calls her "a friend of mine that's a normal girl. ... That's one of my best friends. I have all these girls who I hang out with all the time."

"I have to deal with that anyways," she said – her friend is not. "This girl doesn't even have to deal with that, and it's so hard," said Cyrus. [Now] she has to go to school and deal with this crap."

Concerning the photos themselves, Cyrus said, "It's two girls at a sleepover, and if all of a sudden that's bad, then what is the world coming to?"