The Ferrari driver had two near-identical accidents at Sainte Devote during the Monte Carlo weekend.
The first occurred in final practice, ruling him out of qualifying due to the level of car damage, while the second ended his race.
Ferrari immediately suspected the race incident was caused by a technical problem.
But Massa said despite the accidents' similarity, their causes were completely different and he took full responsibility for the first.
"It was two accidents which look really similar from the television but they were completely different accidents," he said.
"The first one I had just locked wheels over the bumps and then went straight and hit the guardrail.
"In the second one I had a suspension problems. I had two accidents in the same place, that looked similar."
Massa was checked in hospital after the second crash, but said he was fully healed for this weekend's Canadian Grand Prix.
"The good thing is I am fine," he said. "I just felt a bit of pain in my neck afterwards - it was two crashes in the same direction - but it was just muscles."
- Motor Racing