The Tongan was sent off in the last regular season match against Connacht in Galway on 7 May.
He accepted that he had committed an act of foul play which had warranted the red card and the disciplinary committee found that Puafisi had committed an act of foul play, by recklessly striking an opponent with his head while clearing-out.
It means the tighthead will miss this Saturday’s return to Galway to face Connacht in the semi-finals and the final at BT Murrayfield should Glasgow reach it.
The all-Welsh disciplinary committee determined that the offence merited a lower-end entry point of a four-week playing suspension and that, as there were no aggravating factors, applied a reduction of one week.
Meanwhile, both Guinness Pro12 semi-finals this weekend will be played in front of sell-out crowds with close to 8,000 supporters at the Sportsground in Galway and 19,100 at the RDS in Dublin for the Leinster v Ulster play-off on Friday.
Wales lock forward Bradley Davies is to leave Wasps and take up a national dual contract with the Welsh Rugby Union and Ospreys for next season.
The 29-year-old second row is set to return to Wales after the Aviva Premiership side reached an agreement to release him a year early from his current deal, having signed from Cardiff Blues in 2014.
In England, Bath have announced head coach Mike Ford will leave the club at the end of the current season.
Ford, who had three years left on his contract, will depart after a disappointing campaign in which his team finished ninth in the Aviva Premiership.
Ford, who is the father of Bath and England international stand-off George, joined the west country club as first-team coach in 2012 and has been head coach for the last three seasons.