Davy Russell has been issued with a caution following an inquiry by the referrals committee of the Turf Club over an alleged incident involving the treatment of his mount Kings Dolly at Tramore on 19 August.
Footage appeared to show the jockey striking the horse at a practice flight before the Flynn Hotel Group Mares Handicap Hurdle at the Friday evening fixture, subsequently creating a stir on social media.
The raceday stewards were not aware of the matter, but the Turf Club has the authority to look into the matter and take retrospective action where appropriate.
The incident was fully investigated and the referrals committee convened at Killarney on Saturday.
Denis Egan, the Turf Club's chief executive, told Press Association Sport: "The decision was that he (Russell) was guilty of rule 272(i) and he has been issued with a caution.
"They (the referrals committee) accepted the explanation he gave, in that he wanted the horse to concentrate and that it was inappropriate to use the whip in the circumstances.
"He wanted the horse to concentrate and he used his hand. He accepted that was inappropriate."