The Wales international is being linked with a return to Cardiff, just three years after leaving for Glasgow, but says he is looking to sign a new deal with the Hoops despite the Bluebirds moving into the English Premier League.
"It's just rumours at the moment. There has been nothing official," he said of the Cardiff link.
"A lot of players want to play in the Premier League. It does attract people but, at the moment, I'm with Celtic and I'm just concentrating on a big week ahead of me.
"We still haven't actually spoken to the club [about a new contract]. My agent has been away and the club has been pretty busy as well with sorting out new players.
"Hopefully I will be next and sort something out. In the next couple of weeks, if we could sort something out, it would be brilliant."