Lawes will miss England's Pool B games against Georgia on Sunday and Romania on Sept. 24 following the disciplinary hearing in Auckland, but will be available for the final first-round match against Scotland.
"It's disappointing that we lose a player, obviously. A good player for us," England team manager Martin Johnson said. "We have cover there clearly, but it's disappointing."
The management has not yet decided whether to appeal against the verdict since England had just finished training in Queenstown when the verdict was announced.
"I've briefly spoken to the guys up there," Johnson said. "We'll wait until the guys get back and go from there. I've not got the detail, so we'll see what they say and see where we are with it."
Lawes was cited by match disciplinary commissioner Murray Whyte over the incident at the end of the first half in England's 13-9 opening win over the Pumas on Saturday.
Lawes was forced to fly to the northwest city from England's training base in South Island resort town Queenstown to attend the hearing.
Although he could have been suspended for far longer and will be available for what looks like being England's toughest remaining first-round match, Johnson was still disappointed with the verdict.
"It's a fast-moving game and he's started to make what he thought was a try-saving tackle, and we thought whatever contact with the knee was accidental," Johnson said. "They saw things slightly differently."
The suspension opens a secondrow berth alongside Louis Deacon to Tom Palmer or the veteran Simon Shaw.
"The good thing for us squad-wise is that we need to play players," Johnson said.
One of those players who may get an outing against Georgia back in Dunedin is captain Lewis Moody, who missed England's final two warmups and the opening match after injuring his knee against Wales on Aug. 6.
The openside flanker is expected to be fit for the match at Otago Stadium.
"We anticipate him being there," Johnson said. "He wasn't far off last week. He was running around last week and the week before. If you ask the medics, it's always one more week and then one more.
"But you've got to go some time."