Haouas was shown a red card in the 13th minute of France's 32-21 win over Scotland on Sunday for a head-first charge at Ben White's head.
The Frenchman was also shown a red while playing against Scotland in the 2020 Six Nations.
He was brought into the side to replace Uini Atonio (32), who was handed a ban last month.
A Six Nations statement on Wednesday said Haouas "admitted that he had committed an act of foul play warranting the issue of a red card prior to the hearing".
"After reviewing all the evidence, the committee... applied World Rugby's mandatory minimum mid-range entry point for foul play resulting in contact with the head. This resulted in a starting point of a six week suspension," the statement added.
"Having acknowledged that there were no aggravating factors and accepted mitigating factors... the committee reduced the six week entry point by two weeks, resulting in a sanction of four weeks."
Defending champions France, who are fourth in the standings, next face England at Twickenham on March 11. They then host Wales on March 18.