The couple met on the 2010 series of The X Factor where she worked as a backing dancer but the pair split last month.
"I've been trying to deal with it in private," Payne told Now magazine.
"I'm not so much worried about me - whatever happens I'll live and deal with it. I'm more concerned about Danielle because I don't want people harassing her for any reason."
He added: "Obviously she's got a lot on her mind without people saying things on the internet or going to her doorstep.
"She doesn't need that right now... I've asked for people to stay away from her as much as possible so she can deal with things."
Peazer had been the subject of online abuse from One Direction fans during her relationship with Payne.
Payne said: "Twitter twists things a bit. People have a false sense of confidence behind a keyboard.
"Some of the things they say I just can't believe. I think, 'How can you say that? You wouldn't be able to say that to someone on the street, so why say it now?' But it's one of those things."
Fellow X Factor star Leona Lewis has denied rumours that she and Payne are now dating.
The full Liam Payne interview appears in Now magazine on Tuesday, October 23.