"I love you as a human being but I can't give you my vote," Perry told Mr Abbott on Sydney's 2DayFM, after being informed he opposed same-sex marriage.
Mr Abbott was one of a number of Aussie "celebrities" given the chance to ask the US pop star a question today.
He said his "big question" was when would the 28-year-old singer again tour Australia.
"When are you coming back (to Australia)? We need you, we want you," Mr Abbott enthused.
Perry, however, was keener to discuss coalition policy than her music.
"Oh come on, that's not a political question, let's talk about gay marriage," she retorted.
"Now you're interviewing me, Katy," a surprised Mr Abbott replied.
Perry urged voters to speak out against Mr Abbott's stance on gay marriage.
"I said 'hey, I like you as a human being I just don't believe in you policies so that's what a lot of people should be doing'," she told radio host Jackie O, after the chat with Mr Abbott.
"I'm sure he's still a fan, Katy, even though you gave it to him," Jackie O reassured her.
The coalition supports the standard definition of marriage as between a man and a woman, and opposes changing the Marriage Act.
Labor says it would allow MPs a conscience vote on the issue if it wins the election on September 7.
