Brewster, 20, notched his ninth of the season this week and his fifth goal in seven games since joining the Welsh club in January on loan from the Reds.
Cooper bossed England U17s to a World Cup triumph with a side including Brewster, who scored in the final.
He said: “I think it is a question for Jurgen (Klopp) and Liverpool.
“We are very happy with him here and he is very happy to be here. It is working nicely, most importantly for Swansea City Football Club.
“After that it is up to him where he goes. With these young players it's about when you give them their opportunity and we have."