Speaking to Digital Spy at Glastonbury after Beady Eye played an unannounced set on the Other Stage this morning (June 28), the singer also suggested the festival could host a comeback.
"Me and our kid [Noel] still don't speak," Gallagher said, "Gem [Archer] and the lads still speak."
Guitarist Andy Bell added: "It will come down to a conversation."
Gallagher continued: "Without being f**king hippy, it'll happen when it'll happen. If the musical gods want it to happen."
"This question will always be asked," Archer said, with Gallagher commenting: "If it does happen, we'll be match-fit."
Asked if Glastonbury - where Oasis headlined in 1995 and 2004 - would be a perfect venue for a comeback, Gallagher said: "I guess so.
"Wherever it'll be, it will be big. But who's to say it should be big? Maybe it'll be small."
Oasis split in 2009 when Noel Gallagher walked out. Liam went on to form Beady Eye with his former Oasis bandmates and Noel launched a solo career as Noel Gallagher's High Flying Birds.
While Noel has said that he would not reform the band "even if all the starving children in the world depended on it", Liam has said that he would "do it for nowt".
Digital Spy is reporting from this year's Glastonbury with Gaymers Cider. Win tickets to other festivals across the summer on Gaymers' Facebook page.
Photo gallery - Glastonbury 2013 in pictures: