BuddyPress.org

@danielafer use private community plugin or BP lock , it will help to keep your community private for logged in users.
If you do not want the private community approaches you can also use no-index.

function no_index_for_buddypress() {
    if ( is_buddyPress() ) {
        echo '<meta name="robots" content="noindex, nofollow">';
    } else {
    }
}
add_action( 'wp_head', 'no_index_for_buddypress' );