Sources have told ESPN Barca are open to offloading the Dutch international, initially asking for a total package, including add-ons, of up to €100 million.
"The only thing I know from Frenkie is that he wants to stay at Barca," Koeman told TV3 on Monday.
"In fact, a couple of days ago he said that: 'I want to stay at Barca.' But I don't know if Barca want to sell Frenkie de Jong or if they just need the money -- because I think he is one of the few players they have that has such a high price."
Koeman coached De Jong when he was in charge of the Netherlands and then gave him a prominent role when he took over at Barca in the summer of 2020.
However, following the dismissal of Koeman last November and the appointment of Xavi Hernandez, coupled with the emergence of Pedri, Gavi and Nico Gonzalez, there has been occasional criticism of De Jong's form.
"It could be he has not completely adapted because of the position issue, he was playing further back," Koeman added.
"But he had a moment, in January and February, when he produced some great performances. He is a great player, but the situation at Barcelona is complicated."
Behind Barca's willingness to listen to offers for De Jong, who joined from Ajax for €75m in 2019, is their delicate financial situation.
Sources have confirmed to ESPN they expect to sell 10% of their income from LaLiga television rights for the next 25 years for over €200m this week, but they still need to bring in more money to execute the plans they have in the transfer market.
They could sell another 15% stake in their television rights or up to 49% of subsidiary company Barca Licensing and Merchandising, as authorised by members this month, but transfers and wage cuts are the quickest way to increase their LaLiga spending cap.
Chelsea defender Andreas Christensen and AC Milan midfielder Frank Kessie are due to arrive on free transfers in the coming days, while talks are ongoing to sign Bayern Munich striker Robert Lewandowski.
As things stand, though, Barca are still operating with -€144m spending cap -- the only negative limit in the league.
As a result, they can only spend a fraction of what they raise of save, and are unable to register new signings Christensen and Kessie.