add_filter( 'arm_check_member_status_before_login', 'your_function', 10, 2);
function your_function($user_status = true, $user_id) {
    //$user_status True OR error message.
    //$user_id User ID.
    if($user_id == 14) {
        global $arm_errors;
        $arm_errors->add('access_denied', 'You are not authorize to login.');
        $user_status = $arm_errors;
    }
    return $user_status;
}