Having heard submissions from Glentoran and the match officials and also having viewed footage, the committee was not satisfied that an error had occurred.
However, under article 16.7 of the code, it opted to suspend half of the sanction for six months.
Novo's three-match ban will start on Monday, 3 April.
Glenavon have the right to appeal against the disciplinary committee's decision.
Glentoran striker Nacho Novo has had a six-match ban for an attempted head-butt halved to three games by the Irish FA's disciplinary committee.