The 29-year-old left Bootham Crescent in the summer after indicating he would not sign a new deal and has been linked with a number of clubs including the Cod Army, Rotherham and Burton.
Walker, who helped fire the Minstermen back into the Football League in 2011/12, has been a long-time target of the Highbury Stadium club, who have tried to sign him on several occasions over the last few years.
And the striker would be keen on a move to the west coast.
"I leave things like that to my agent, but there are a few clubs interested so we'll see what happens," Walker said.
"I'm definitely ready for a new challenge and I just want to play at the highest level possible and do the best I can."
Alexander has had a busy summer as he shapes his squad for an assault on League Two next term, having already signed six players, including Walker's former York team-mate Matty Blair.