Maybe
$dm = $this->get('doctrine_mongodb')->getManager();
$qb = $dm->createQueryBuilder('AcmeDemoBundle:User');
$paginator = $this->get('knp_paginator');
$pagination = $paginator->paginate(
$qb,
$this->get('request')->query->get('page', 1)/*page number*/,
10/*limit per page*/
);