Koke believes teammate Antoine Griezmann is happy at Atletico Madrid, but warned that any player who isn't focused on the club should leave.
Asked about his opinion on Griezmann's future, Koke said Atletico only want players to stay if they are totally committed.
"Talking about Griezmann, he had the chance to leave after the last season, but he didn't. So I think that means he likes it here," said Koke, who has been with Atletico since he was eight years old.
"We always say if somebody doesn't like it here, he's free to leave. The club and I want the best, we want committed players.
"Those who aren't [committed], just have to ask for a transfer. We only want players who are 100 percent focused here.
"[Griezmann] does look committed to Atletico. In the last month, the reality is that we haven't been any good and little by little we will improve."
Atletico Madrid return from the international break with a derby against Real Madrid, with both clubs chasing Barcelona and Valencia above them in the table.
Looking ahead to Saturday's game, Koke added: "We haven't seen their best version yet but they have amazing players and always give their best. [I expect] a Madrid who will give everything and come to the Wanda Metropolitano with a lot of desire.
"Every game against Real Madrid is special. The essence of a derby, even when you've played in a lot of them, is never lost."
Atletico are fourth in the table but level on points with Real, and Koke believes the game provides a good opportunity for his side to kick-start their season.
"We're good. It's true that the past month we haven't shown our best level. We did some great things and we did some bad things," he said.
"This international window has been good for us to improve, to analyze our mistakes."