England midfielder Barkley, 23, has just over 12 months left on his contract at Goodison Park, but is yet to agree a new deal with the Toffees.
Barkley has been linked with a summer move, amid interest from Chelsea, Manchester City and Arsenal.
Koeman has been consistent with his stance that he wants to keep the player, who has scored six times this term, but will sell if an extension can’t be agreed.
“If you offer a player a new contract, a good contract, it means you want to keep the player,” said Koeman.
“I don’t need to explain more. If we didn’t want him to stay longer we wouldn’t offer him a new contract.”
Asked whether he was confident Barkley would put pen to paper on a deal which is set to expire next summer he said: “No.
“No because it’s a long time he’ been thinking about his future. But OK I’m not worried because I like to work with players who like to stay and we are looking for players in that position.
“Even if he stays he’ll have more competition next season.
“It’s after the game or Monday. And then we will know.”
Koeman is already making plans for the summer, with the Dutchman hoping to gatecrash the top six next term.
“We have had several meetings and know what we want,” he said. “It’s up to the board now to make the deals.
“If we can do our business this summer the team for next season will be really strong but it’s difficult sometimes.
“We’re already two or three months into getting a picture of what we need. Let’s hope we do good business.”