The Chelsea forward felt the need to speak to his teammate at half time of the World Cup Group G match on Monday as the Red Devils were struggling to break down their opponents.
Hazard suggested that Lukaku had been "hiding up front" in the opening 45 minutes, before responding with two goals in the second half in what turned out to be a comfortable 3-0 victory.
Asked to explain his comment, Hazard told Sky Sports News: "As the captain, even if I am not the captain I can talk, on the pitch I try to give my best, if I can help players to be better I will.
"I just told Romelu if we want to win the game we need him, not just as a scorer to score goals, but we want him to be involved in the build-up. We just talked normally and we won the game in the end so it was fine."
Hazard and Lukaku are expected to start Belgium's second group outing against Tunisia on Saturday afternoon.