The 18-year-old has been in superb form for the Dons this season and manager Craig Brown was keen for him to commit his future.
However, he has told Brown that he sees his future elsewhere and with his current deal due to expire at the end of the season, the club may attempt to sell him on in January.
Brown told Aberdeen's official website: "The club made the player what was the best offer they possibly could and it's very disappointing that he has chosen to see his future elsewhere.
"It was indicated to the club that Ryan believes he is ready to play at a higher level than the SPL and I have to say I think that is the wrong decision.
"He would be far better to continue to learn his trade here with Aberdeen and I only want players here who are 100% committed to Aberdeen Football Club."
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