While most drivers decided to test out conditions on intermediate tyres on the wet Catalonia circuit, Hamilton chose to give it a skip.
There has been some animosity between Rosberg and Hamilton in recent years, largely down to the toxic nature of their relationship during Rosberg’s final season in the sport when he pipped Hamilton to the world championship.
Rosberg believes that Hamilton was wrong in his decision not to try out the car during the wet conditions as opposed to other drivers.
“Look, now Lewis is in a rush to get his belts on because he was out of the car,” Rosberg said.
“I think Bradley [Lord, Mercedes communications director] should have had a word with him.
“Maybe this is Bradley, that’s why Lewis is back in the car.”
Rosberg then revealed that he had spoken with Mercedes after the session.
“Lewis could have perhaps made a little bit of a better effort in FP3 and been out there more to learn a bit more,” he said.
“It was in fact his decision to be in the garage for all that time and to also go out a bit late on the softs. So they [Mercedes] did say it was perhaps not 100 percent ideal.
“But then again, as a seven-time world champion you could allow yourself to do that.”