The two clubs have already reached agreement over a fee rising to €5m. Real Madrid would pay €2.5m up front with a further €2.5m due in bonuses.
However, AS says the deal is now suspended due to the player's personal terms.
And should Soro not pull back from his demands, Real Madrid are prepared to jettison the deal.
Soro is initially being lined up for Raul's Castilla squad.