Koeman has spoken about Fati's recovery process with the Barcelona forward sidelined since March with a knee problem.
"Out of respect for Ansu, I'm not the person to speak about his recovery, we have to show some respect," the Dutch coach said in a press conference.
"If there is news, there will be a medical statement from the club. The important thing is that there's no pressure on his comeback, he has a big future ahead of him and we have to do things the right way."
Koeman didn't seem especially happy with the news that came out this week saying there had been a relapse given his calls for "more respect."