The veteran forward is available after leaving Australia's Sydney FC.
"Two years ago it was interesting and it would be interesting again," Del Piero told The Sun.
"If we could talk then great. If you want I'll give you my phone number and you can pass it on! Celtic are a great team and I've always enjoyed playing in Scotland so who knows?
"We were in contact with Celtic but it didn't come to anything. But I was very interested in moving to Scotland."
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