The 18-year-old, who is allegedly close to signing a new deal with the Catalan giants, has featured in his side's last four matches in all competitions after recovering from injury.
Koeman has branded the attacker "a young player with a lot of quality", and Fati has found the back of the net on two occasions in his three league appearances since returning.
Barcelona are now preparing to face Dinamo Kiev and Real Madrid in two hugely important fixtures, but the Catalan club's head coach has insisted that Fati is still not 100% fit and will not be over-used.
"It's impossible for Ansu Fati to play three full games in seven days," Koeman told reporters. "He is a young player with a lot of quality, and one that stands for the future of this club."
Fati has scored 15 goals and registered six assists in 47 appearances for Barcelona in all competitions. body check tags ::