In a conversation with Jesuits published by Italian Jesuit journal Civiltà Cattolica, he said "sometimes prophetic audacity weds with diplomacy, with a certain work of conviction" and is "called on to attack corruption".
The pope also said he tended towards pessimism and "God's consolation is the best antidepressant".
He added that today "great politicians" were lacking, those who "do not fear struggles or dialogue".
Francis said "great politics is not polarisation".