Ajax have told Roma to increase their bid for Maarten Stekelenburg or look for a new goalkeeper elsewhere.
The two clubs met earlier this week to discuss the Dutch international, but no agreement was reached over terms.
"We clearly know that Maarten, who is a great goalkeeper, wants to leave," Ajax sporting director Danny Blind told Telegraaf.
"We are giving him the possibility to join another club, but it has to be at the right price.
"Although his contract expires in June 2012, he's worth more than €5m."
That is believed to be the offer tabled by Roma for the 29-year-old. It's understood that Ajax are looking for closer to €10m.