Du Plessis, who was fined his entire second-test match fee, was cleared to play in the third and scored a defiant century on Thursday's opening day after walking to the wicket to a chorus of derision from the Adelaide crowd.
“Faf has decided to appeal the match referee's decision after he and his legal team had studied the written reasons provided by the match referee,” CSA chief executive Haroon Lorgat said in a statement.
“In his mind, Faf is clear that he did not alter the condition of the ball nor did he intend to do so and that the match referee was not correct to find him guilty. He is understandably feeling aggrieved.
“CSA will support him to appeal the decision before an independent Judicial Commissioner as there are issues relating to fair and just process, interpretation of the rules, science and performance that needs to be considered,” Lorgat added.
On the eve of the third test, Du Plessis denied cheating and said he had been made a “scapegoat”.
“I still completely disagree with (the verdict). I felt like I've done nothing wrong. It's not like I was trying to cheat or anything, I was shining the ball. It's something that all cricketers do,” he told a news conference.
Du Plessis was found guilty following a lengthy ICC hearing in Adelaide on Tuesday.
The 32-year-old, standing in for injured regular captain AB de Villiers, was charged by the ICC on Friday after television footage appeared to show him applying saliva to the ball while sucking on a sweet.
After hearing representations and evidence from the umpires at last week's second test as well as Marylebone Cricket Club (MCC) head of cricket John Stephenson, ICC match referee Andy Pycroft found Du Plessis guilty.
The London-based MCC remains the copyright holder to the laws of cricket.
“The decision was based on the evidence given from the umpires, who confirmed that had they seen the incident they would have taken action immediately, and from Mr Stephenson, who confirmed the view of MCC that the television footage showed an artificial substance being transferred to the ball,” the ICC said in a statement.
Three demerit points had also been added to Du Plessis's disciplinary record, the governing body added.
If a player accumulates four-to-seven demerit points within a two-year period they are converted into two suspension points, which brings a ban for one test or two one-day internationals or Twenty20s, whatever comes first.
Du Plessis, who pleaded not guilty to the charge, had previously been sanctioned for ball-tampering after a test against Pakistan in 2013.
He was then fined 50 percent of his match fee after he was caught on camera rubbing the ball against a zip on his pocket on the third day of the match in Dubai.
The ball-tampering charge angered the South African camp and senior batsman Hashim Amla launched an impassioned defence of Du Plessis on Friday in a public show of solidarity with the entire team standing behind him.
Cricket South Africa complained on Monday that Du Plessis had been subject to “harassment” by Australian media after a TV reporter was involved in a physical confrontation with a team security guard at Adelaide Airport.
REUTERSSouth African cricket officials support Faf du Plessis’s decision to appeal match referee’s ball-tampering decision.
Original source: Cricket SA backing ‘aggrieved’ Faf