The Brazilian club have been interested in bringing the forward back to his former club for some time, and have been especially keen to strike a deal since selling Neymar to Barcelona for £48.6million.
Despite having funds available, Santos believe Milan are asking too much for Robinho and are also unhappy with the player's wage demands.
It is reported that Milan are demanding €10million (£8.6m) for Robinho, who is 29 and only has one year remaining on his contract.
"In this moment there is an important distance to complete the negotiation," Santos president Luis Alvaro de Oliveira told Globo Esporte.
"Milan are asking a lot and the player too has a salary request which does not seem right to us.
"We have no intention of being foolish. We can talk only if Milan come back to reality."