Speaking on his YouTube channel, Rosberg said: "Vettel was screaming 'I had dirt on my tyres, I was out of control, where do you want me to go? I was struggling to control the car, and I couldn't see Lewis.'
"Okay great. But Lewis is there. The rule says when you go off the track, you need to rejoin safely. So Vettel went all the way across and I think he could have easily left a little bit more space, especially in the latter phase like after Lewis started braking. He could easily have left more space, but he didn't.
"He went right, right, all the way there and left hardly any space to Lewis. And so Lewis saw it as a dangerous situation because Vettel was coming more and more, so he had to back out of it.
"I looked at the replay many, many times. Lewis would have been in the wall had he stayed there because right afterwards Vettel continued to move over more and more and it was so tight that Lewis would have touched either Vettel or the wall.
"So it is very, very clear that unfortunately it was an unsafe return to the track. That is the rule. You have to return safely and that is the way it is. A penalty is deserved in that case."
Rosberg said he had spoken to his father Keke about the incident, and reckoned that even suggestions Vettel was not entirely at fault did not stand up.
"My father said to me, 'It's probably 60/40 – 60 penalty, 40 not.' I asked, 'why 40 not?' 'Well, because he was just out of control and he could not do better than that because he had dirt on his tyres and was coming from the grass and everything'.
"I said, 'Okay, fine I know that. But so what? You still have to return safely and if you are out of control then you are not returning safely.'
"So that is it. Penalty deserved. It is not a valid excuse: 'Oh I was out of control, I had dirty tyres and I couldn't see Lewis.' It is not a valid excuse unfortunately. So the penalty is full deserved. Absolutely full[y] deserved penalty."