Assalamu alaikum
Probably one of the dua that are permitted is when they sneeze, that is ' may Allaah guide you' whereas a complet dua should be said to a muslim
Anyway it is an authentic sunnah of the Prophet to call upon Allaah to guide the kuffars especially those who are 'passive':
- He sallal Allaahu alaihi wa sallam had made du'a to umar ibn Khattab before he embraced islam
- etc.
