An apprentice jockey has blamed a "brain fade" for punching a horse at a South Australian race meeting, his action earning him a two-week suspension amid calls for a lifetime ban.

Dylan Caboche was observed hitting his mount She's Reneldasgirl ahead of race two at Port Lincoln on Wednesday.

Thoroughbred Racing SA conducted an immediate inquiry and suspended Caboche but animal rights groups have described the penalty as grossly inadequate.

The RSPCA is also investigating to see if animal cruelty charges can be brought.

Issuing an apology on Thursday, Caboche, 22, said he was "gutted" and appreciated his actions were completely unacceptable.

"No matter how difficult my mount was, it just can't justify what I did," he said.

Caboche's punch, delivered to the horse's mid-section, was caught on camera behind the starting gates at the Port Lincoln racecourse.

He told Seven News that striking a horse was "obviously not the right way to go about things".

"It was a brain fade and it shouldn't have happened," he said.

Chief Steward Johan Petzer said TRSA would not condone or allow such behaviour and took the welfare of horses seriously.

"While we understand there will be a lot of debate over the penalty we can assure the general public the stewards' panel took into account all the factors before determining an appropriate penalty," he said.

Petzer said Caboche would also be provided with the services of a sports psychologist and the TRSA said the ban imposed on the jockey should serve as a warning to others.

"It is hoped this penalty, which will remain on the rider's record and will impact his earning ability, will send a strong signal to others," it said in a statement.

Caboche will not appeal the ban but could face further sanction, with Australian Jockeys Association chairman Des O'Keeffe to ask for a code of conduct hearing.

Caboche's boss, Morphettville-based trainer Ryan Balfour, said he was prepared to help the embattled apprentice describing his "moment of madness" as completely out of character.

She's Reneldasgirl's trainer Allan Jarvis said he would leave the matter to racing authorities.

But the RSPCA called for a tougher penalty and the Coalition for the Protection of Racehorses said Caboche should be banned for life.

"If jockeys can't control their tempers, they don't deserve to be on the racetrack," communications manager Ward Young said in a statement.

RSPCA chief executive Paul Stevenson said the two-week ban was inadequate and should be reviewed.

"If stewards want to send a message they need to hand down a much stiffer penalty, one that reflects the community's outrage over this incident," he said.