Moyes insists Barkley will continue to play for the U-18s side in the FA Youth Cup, after scoring in their 2-1 win over Crystal Palace on Tuesday.
"It's important that he plays with boys in his own age group as well and that will continue to happen," he said.
"He'll continue to play in the FA Youth Cup unless he's in the team and I need to use him, and he'll train with us still.
"The academy has had a great record of developing not just players, but a real top end level of players. It's great. But also part of that is we don't have a big squad so if you are a good young player you have a chance of being put in early, and in some cases too early."