Abbott, who joined Harlequins from Wasps earlier this year, will be unavailable until October 3.
The suspension rules him out of Quins' Guinness Premiership games against his former club next Sunday, Leicester on Saturday week and an EDF Energy Cup appointment with Llanelli Scarlets.
Abbott was cited for a dangerous tackle on London Irish scrum-half Paul Hodgson during his side's Premiership opener at Twickenham 10 days ago.
Referee David Rose sin-binned Abbott after the 23rd-minute incident, but the player was then reported by independent citing officer Peter Larter.
Abbott, capped nine times and a member of England's 2003 World Cup-winning squad, pleaded guilty to the charge when he appeared before a three-man RFU panel in London.
It is a considerable blow for Quins, who are currently 11th in the Premiership following defeats against Irish and Gloucester.