Singer made X-Men and X2: X-Men United, but passed on the third installment so he could make X-Men: The Last Stand. South African filmmaker Gavin Hood made another spin-off, X-Men Origins: Wolverine which was released earlier this year.
"I'm still looking to possibly returning to the 'X-Men' franchise. I've been talking to Fox about it," Singer said at a talk at South Korea's Pusan International Film Festival.
"I love Hugh Jackman. I love the cast," he said, referring to the Australian actor who plays Wolverine.
Singer said he enjoyed making science fiction and fantasy movies because they allowed him to discuss serious issues through entertainment. He said the "X-Men" series, which follows a group of mutants with superpowers who struggle to fit in with humans, is about tolerance and social structures.
He said he likes to "trick audiences into thinking they're seeing fireworks, but they're learning about themselves and listening to what I have to say."
"The excitement about working in science fiction and fantasy is - the stories, if they are good, are about the human condition," Singer said.