"I am a huge Lewis fan because he is a super promoter of the sport," Ecclestone said in a conversation with Hamilton's Mercedes team mate Rosberg published on the official formula1.com website.
"From a pure business aspect -- sorry Nico if I have to say this -- you are not so good for my business."
When Rosberg told Ecclestone that is a "hard call", Ecclestone pointed to the lack of a German Grand Prix this season.
"It sounds harder than it meant. Unfortunately you don’t have the German fans on your side. As the cancellation of the German Grand Prix indicates, Germany is a terrible market for Formula One.
"On the contrary Lewis is a hero in the UK. The British love Formula One. Sebastian is also not doing much for F1. People hardly recognise him on the street."
Double champion Hamilton, who was on pole for Sunday's showcase Monaco Grand Prix ahead of Rosberg and Ferrari's Vettel, has become a familiar face in celebrity magazines and websites for his jet-setting lifestyle.
The 30-year-old Briton has made friends in Hollywood and the US music scene as well as the fashion industry.
"I still believe that Lewis is the best champion that we have had in a long, long time. He manages to get to all different walks of life: red carpet, fashion business, and music -- you name it," Ecclestone told Rosberg.
"That is not your fault or his. You two are just very different characters.
"Nico is not seeking the limelight as Lewis does. Lewis wants to be famous," explained the 84-year-old Briton. "I am happy that we have somebody like Lewis. I also couldn’t be like Lewis. I don’t like gold jewellery."
Ecclestone also said the team principals should be more prominent, and said new Ferrari boss Maurizio Arrivabene is a character "only for himself and not for Formula One".
Image: Lewis Hamilton with Nicole Scherzinger.
Photograph: Vittorio Zunino Celotto/Getty Images