Barca failed in their summer-long pursuit of Coutinho, after losing Neymar to Paris Saint-Germain in a world-record transfer,
The 25-year-old submitted a transfer request and the La Liga giants had three bids rejected, as Liverpool stood firm.
Grau however sayd they have not given up and will return for the Brazilian next year.
“We are ready to buy Coutinho in the winter market or any player the technical staff request,” Grau said.
“But it is important to adjust ourselves, so if there are to be arrivals, there must be exits as well.
“We must forget about the price paid for Neymar last summer. After taxes we received about €188m in income and a direct financial impact on the club’s treasury of €144m.”