The 19-year-old singer has kicked off a 10-month tour and has been advised by the management to cut down on boozing and smoking, reported Daily Star.
The teenage pop star's father Des told him that he ought to "stop the bad boy image because it will backfire".
His father even advised him to "treat girls right or you'll get a love rat image".
"Des is worried that Harry is emerging as a lad who treats girls badly, dumps them and moves on without much remorse," a source said.
"He told Harry to ride the wave and live the dream, but he is concerned his son is getting a bad reputation, which is unjustified as he is a kind-hearted soul.