FRANKFURT — German Bundesbank President Jens Weidmann criticized the European Central Bank’s decision to buy private-sector bonds and chastised France for budgetary laxness, taking a hard line against new stimulus just before high-level International Monetary Fund meetings.

Mr. Weidmann’s comments, in an interview with The Wall Street Journal, expose some of the deep rifts that have plagued the 18-member eurozone since its debt crisis erupted nearly five years ago. While France and Italy, struggling with stagnant economies,...