The player will miss for South Africa's fall fixtures.
South Africa front-rower Wessels has been suspended of nine matches for grabbing opponent Josh Murphy's private parts during the Bulls' United Rugby Championship win over Connacht.
This event happened in the 18th minute of the narrow victory against Connacht on last Friday, with Connacht forward Josh Murphy being shown a 20-minute red card after reacting angrily by hitting the South African on the head.
Following Murphy complained to referee Mike Adamson, the contact was reviewed by the television match official, who determined insufficient clear footage.
Wessels stayed on the field until he was substituted in the second half of the match.
While the United Rugby Championship confirmed that the Irish player's temporary sending-off was withdrawn by a disciplinary panel, the Springbok was found to have violated law 9.27, which states:
"A player should not do anything that is against the principles of fair play. This includes grabbing, pulling or compressing the genitals."
The panel were satisfied that the contact reached the red card threshold and warranted a three-month ban, the minimum ban under international rugby rules for such an offence.
Nonetheless, the player's ban was reduced by 21 days because of his good conduct during the proceedings and his clean disciplinary history.
Wessels and the Bulls are entitled to challenge the decision, but as it stands, the ban will prevent the young player out of the South African national team's autumn Tests against the Brave Blossoms, France, the Azzurri and the Irish team.
Wessels will additionally be absent for the his club's URC games against Glasgow, the Emirates Lions and the Sharks, as well as Investec Champions Cup games with Bordeaux and Northampton.
The prop has won ten international appearances for the Springboks and was part of their Rugby Championship-winning team during the recent tournament.
Murphy, meanwhile, is eligible to play against the Irish rivals in this weekend's inter-provincial derby after being cleared.
