The Ferrari driver dropped to the bottom of the field after spinning under braking at the end of the main straight.
Massa nearly hit Ferrari team-mate Fernando Alonso in the incident.
The Brazilian said he was left with nowhere to go and had to force the spin to avoid an accident with the Mercedes of Rosberg.
"There were a lot of cars in the tow, and I was in the tow from Fernando and then there were cars on the side, a little bit quicker, passing the two Saubers," explained Massa, who recovered to finish ninth.
"So I moved to the right of Fernando and then I was to his side, and under braking I braked a little bit later than them but everybody was on the side like this.
"I was on the right and I couldn't go to the left and there were cars on the corner so I was going to hit Rosberg.
"And then I had to turn the car not to hit him and I spun. It was lucky that nobody hit me, but for sure I lost the race there."
ALONSO NOT BOTHERED
Alonso, who avoided contact by the smallest of margins, played down the incident.
"It was nothing important," he said. "We arrived to Turn 3, all the cars together. I don't know if Felipe had some contact with some cars on the inside. I tried to avoid him to not take any risk and nothing happened.
"It was zero problem and it didn't change anything in my race because I was behind Nico already.
"For Felipe, maybe he lost some positions because he only finished ninth at the end but I don't know how much better we could have finished in terms of team performance for the constructors' championship, which is important."
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