Attwood, who admitted the charge at an independent European Rugby Cup disciplinary hearing in Dublin on Thursday, is suspended until February 21.
It means the 23-year-old, who is a member of Martin Johnson's England elite squad, will be unavailable for the opening RBS 6 Nations Championship games against Wales and Italy.
Attwood toured Australia with England last summer and did not feature in the two-Test series, but he made his international debut as a replacement against New Zealand at Twickenham two months ago.
Toderasc suffered facial injuries as a result of the first-half incident at Kingsholm. La Rochelle officials initially feared he could lose the sight in his right eye, although those concerns proved unfounded.
Attwood admitted the citing complaint, but maintained he had not intended to make contact with Romanian international Toderasc's face.
Independent judicial officer, Welshman Robert Williams, considered video footage of the incident, medical reports relating to Toderasc's injuries and testimony from Attwood.
Williams found the offence was in the top-end range for the offence's level of seriousness and decided on an entry point of 18 weeks.
But after considering mitigating factors, including Attwood's guilty plea, the player's remorse and what was described as his "exemplary conduct" at the hearing, Williams made a 50% reduction and decided on a nine-week ban.
The period of suspension was back-dated to begin on the day of the match - December 19 - which takes into account Attwood's suspension by Gloucester, a two-week sentence which they imposed shortly after the game.