The veteran openside will miss the Welsh derby with the Scarlets a week on Friday, as well as the Heineken Cup trip to Castres this weekend but will be free to turn out for Wales against Australia, South Africa, Fiji and New Zealand.
Williams had being charged under the IRB’s Law 10.4(a) ‘A player must not strike an opponent with the knee(s)’ following an incident involving Chris Paterson in the Euro opener with Edinburgh last Saturday.
He is free to play again on October 27 meaning he would be available for the Blues’ trip to Aironi two days later if Wales coach Warren Gatland wants Williams to get game time before the opening Test against Australia on November 6.
Scarlets flanker Jonny Fa’amatuainu will also miss two Magners League ties and the second round of the Heineken Cup following a dangerous tackle on Perpignan wing Adrien Plante during the impressive bonus-point win over the French giants.
The Samoan international will be unavailable for the trip to the Cardiff City Stadium and the home tie with Glasgow Warriors, plus Saturday’s match at Leicester.