Chris Munce has described a stewards' decision to suspend him for a month for improper riding as "outrageous".

Munce left Doomben on Saturday fuming after stewards found him guilty of improper riding, alleging he altered his whip action aboard Platinum Mint and made deliberate contact with Magic In Motion passing the winning post in the final race.

Platinum Mint finished second to Anna Lizzie in the Ormiston College Old Collegians Plate (1350m) while Magic In Motion, ridden by apprentice Anthony Allen, finished third.

Munce pleaded not guilty and said he had never faced stewards on an improper riding charge in a career spanning more than two decades.

"No way known to man did I do it deliberately ... this is amazing," Munce told acting chief steward Daniel Aurisch.

"I think you should think long and hard about this. A suspension for something like this is outrageous."

Munce told stewards Platinum Mint was hampered by Magic In Motion in the final stages and denied striking Magic In Motion intentionally.

"I can't see how you can be comfortable with saying it's deliberate," he said.

"He impeded my action by coming out to meet me. It happens at every race meeting.

"I kept a straight course. He comes out, the horses get tangled up and that's the end result."

Aurisch told Munce the panel believed his normal whip action changed as the horses crossed the line.

"In our opinion there was no provocation for what occurs after the winning post," Aurisch said.

"There has to be a general deterrent to riders to desist from this conduct in races."

Munce's suspension started after Saturday's meeting. He can resume riding on October 15.