Thomson will miss the All Blacks' Test against Italy in Rome on Saturday but he will be available to face Wales and England on the remainder of New Zealand's European tour.
The Thomson verdict stood in contrast to the eight-week ban handed down earlier in the day to Australia lock Rob Simmons for a "tip" tackle on France flanker Yannick Nyanga.
Thomson was yellow carded for making contact with Scotland's Alasdair Strokosch's head during New Zealand's 51-22 victory at Murrayfield and later cited for the incident.
The judicial officer, Jean-Noel Couraud, upheld the foul play citing and deemed the offence to be at the lower end of the scale of IRB sanctions.
Thomson was given a two week ban, reduced to one week on account of his conduct in the disciplinary hearing - a suspension described by former England hooker Brian Moore as "ludicrously lenient".
IRB chief executive Brett Gosper responded to Moore and others who registered similar complaints over the verdict on Twitter.
Gosper wrote: "The IRB will review this case as it is a match under our jurisdiction. If we decide to take action we will make it public."
Samoan centre Eliota Fuimaono-Sapolu raged at the Thomson verdict and compared it with the three-week ban he received from the Rugby Football Union last year for tweets about Owen Farrell.
"I got 3 weeks for sarcastic tweets. So had I just rucked Farrells head I would have got only a week? Its just so comical these days," Fuimaono-Sapolu said.
Simmons was cited for a "tip" tackle on Nyanga after coming on as a substitute in Australia's 33-6 defeat to Les Bleus.
At a hearing in London today [Wednesday], judicial officer Robert Williams decided the offence was at the high end of the IRB's sanctions scale and suspended him for eight 'active' weeks.
The ban recognises that Simmons was not scheduled to play after the end of Australia's current European tour and so was extended to February 24.
Simmons' absence leaves the injury-hit Wallabies down to just two available locks for Saturday's Test against England at Twickenham.
Both Thomson and Simmons have a right to appeal.