Is there a way to handle user/group management on Project level ?

We need to be able to manage user access on the project level.
eg.

We have the Project A and the Project B.
There is 10 user with access to the team account Some_Team.
5 users belong to Project A and 5 users belong to Project B.

We want to be able to grant access to the Project A to the 5 users, and that the other 5 users, that have access to Project B, don't have access to the Project A repositories, vice versa.

Actually, it's only possible to grant and revoke the access to the repositories of a project, not the project itself.