Race leader Rosberg slid off-track at Turn 12 with seven laps to go, handing Hamilton first place and paving the way for the Briton to seal his second title in a row with his tenth win of the season.
"I just got wheelspin," Rosberg explained. "It's never happened to me before, not even in testing. I can't explain it. It's unbelievable. To nearly spin by myself coming off a corner- I don't understand it.
"Obviously that was really, really tough at the time to lose the lead and the win like that. I was feeling really good - it just went wrong. My mistake cost me the win."
Polesitter Rosberg had worked his way back into the lead after slipping to fourth place at the start following contact with Hamilton in Turn 1. Speaking before he had seen a replay of the incident, the German said he believed his team mate had been 'too aggressive' into the uphill right-hander.
"I was ahead mid-corner, and I have a right to the track there," he said. "Lewis was too aggressive, one step too far, and that's not okay."
He also played down the significance of an incident in the post-race podium room, in which he tossed a cap back in Hamilton's direction after the Briton had thrown it onto his lap.
"The cap was nothing, just typical games," Rosberg said.
Rosberg eventually came home in second place after seeing off a late challenge from Ferrari's Sebastian Vettel. However, he remains four points behind his compatriot in the standings with three races to go.