Barcelona vice-president Jordi Mestre admits losing Sergio Gomez last week is "concerning".
The teenager quit Barca to join Borussia Dortmund before last week's winter transfer deadline.
Mestre told Sport: "More than worrying, we are concerned. We do not want them to leave and we work to avoid it, but we will not change. So they can go to another club. We have a sports and economic policy for grassroots football.
"If a player does not want to stay, it will hurt us, because we have trained him and we have helped him to get where he is, but, as (Johan) Cruyff said, who does not want to stay at Barça, let him go.
"Many others were able to leave and they stayed."