Earlier this week, Perry, 32, opened up about her time as a guest judge on "The X Factor" in 2010 in which Horan participated.
Perry's deciding vote pushed Horan forward in the competition, where he was later grouped with Harry Styles, Louis Tomlinson, Liam Payne and Zayn Malik to form One Direction.
The pop songstress had said that the 23-year-old was "always trying to like, get my number, to like, maybe flirt with me, but I'm like, 'I could babysit you. I'm like your mom!'"
"Katy, please stop being mean to me," he joked
"She's just finding any excuse now to just patronise me and go around spreading rumours about me. I just want to be your friend!"
He added that their age difference - nine years - isn't that drastic. "I mean, she is talking like she is about 55 years older than me. She is not that much older than me.