Dear Guillermo,
Probably this one can help: http://wordpress.stackexchange.com/questions/1482/restricting-users-to-view-only-media-library-items-they-have-uploaded
Or this: http://wp-types.com/forums/topic/restrict-editor-role-to-view-own-media-only-in-media-library-on-uploadinsert/
It restricts users to view only the media items they have uploaded. Are you uploading images via a CRED form? In what section in WP admin or in front end where you want to restrict them from viewing other images ?Only media library? Please let me know how it goes.
Cheers,
Emerson