Garbutt, 26, was sent off in the 71st minute of his side's 38-4 loss for punching opponent James Tamou.
The Australian was banned for two games by the Rugby Football League on Monday.
"It's not something that I am about. I don't condone violence and I sought James out after the game to apologise," said Garbutt.
"I accepted the ban and I'm very disappointed I won't be out there with the boys for the next couple of weeks."
"Everyone that knows me knows I'm not the sort that does that kind of thing."

The site at Knottingley, West Yorkshire is to burn fuel from refuse, industrial and commercial waste including wood, said operator Multifuel Energy Ltd.
The Â£300m plant is to create hundreds of jobs over a three-year build and should produce electricity for about 160,000 homes, it said.
The adjoining coal-fired Ferrybridge 'C' plant is to close in March 2016, it was announced in May.
The Secretary of State has granted development consent for the new plant.
Construction is expected to begin in 2016 with about 35 permanent jobs once it is operational.
The power station is expected to produce up to 90MWe of electricity annually by burning 675,000 tonnes of waste that could have ended up in landfill, said Multifuel Energy
It is to be built next to the newly-constructed Ferrybridge Multifuel 1 that stated operations earlier this year.
Multifuel Energy is a joint venture between power company SSE and and waste management company Wheelabrator Technologies.

The death toll doubled over the last two days as officials found more than 100 bodies once waters began receding.
Officials estimate that the floods have affected 450,000 people in the state.
This years monsoon rains have affected millions across at least 20 states in India. The north-eastern state of Assam has also seen dozens killed and hundreds of thousands displaced.
The government has announced aid packages for affected areas and Prime Minister Narendra Modi is due to visit Assam on Tuesday.
He has said the aim of his visit is to find a "permanent solution" to the flooding that Assam faces every year.
The Press Trust of India news agency quoted an official as saying that many affected people in Gujarat had begun returning to their villages.

The 22-year-old headed home from a corner as he scored just his fourth goal in 33 appearances this season.
Former Whites striker Michael Bakare had handed the away side the perfect start, curling the ball into the top corner in the second minute.
Stefan Payne scored at the near post to level before Raggett's winner.
Dover are three points behind Tranmere in sixth, with three games in hand, while Welling remain nine points adrift of safety.

An 18-year-old woman was driving a Toyota Yaris when it was in a crash with a Ford Transit van on the A595 near Bootle at 19:55 BST on Friday.
She and her front seat passenger, also 18, were pronounced dead at the scene.
A third 18-year-old woman, in the back of the car, was flown by air ambulance to hospital where her condition is said to be "critical".
The 51-year-old man driving the van was also flown to hospital, where he is in a serious but stable condition.
The road was closed for six hours for the vehicles to be examined and then removed, Cumbria Police said.
The force is appealing for witnesses.

In previous years crime figures have seen a significant rise during the annual celebration.
Good weather on Saturday meant a larger number of spectators than usual turned out to the event.
However, Insp Stuart Wilson said that other than a "few minor incidents" it had passed peacefully.
He said: "The annual Guid Nychburris celebrations started early with police cyclists escorting about 200 horses through the traffic in Dumfries.
"The good weather meant that there were a large number of spectators out to watch the horses, the crowning ceremony and the parade in the centre of Dumfries but it was a good family atmosphere and there were no policing issues.
"Local police were assisted by police horses and Operational Support Division from Glasgow to make sure the crowds were safe."
Leeds Rhinos prop Mitch Garbutt has apologised for his red card in Sunday's World Club Challenge defeat by North Queensland Cowboys.
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A second multifuel power station has been approved for Ferrybridge.
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Floods in the western Indian state of Gujarat have killed 218 people, government officials have confirmed.
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Sean Raggett's second-half strike earned promotion hopefuls Dover a hard-fought win over relegation-threatened Welling in the National League.
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Two teenagers have been killed and another seriously injured in a car crash in Cumbria.
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Police have praised the "good family atmosphere" among the thousands of people who turned out to watch Guid Nychburris events in Dumfries.