Du Plessis was fined his entire match fee on Tuesday after being caught on camera sucking a mint and rubbing saliva into the ball during last week's second test in Hobart.
"I still completely disagree with that (decision)," Du Plessis told reporters in Adelaide. "I feel like I've done nothing wrong... it's not like I was trying to cheat or anything.
"For me (ball-tampering) is picking the ball, scratching the ball. Shining the ball, I think all cricketers would say, is not in the same place," said Du Plessis.
Cricket South Africa chief executive Haroon Lorgat said he would raise the subject with the International Cricket Council after several leading figures questioned the case against Du Plessis.
"I just think it's opened up a can of warms with what's going to happen now going forward with the game," Du Plessis said. "Something like this needed to happen to create a bit more awareness around it."
However, Du Plessis escaped a ban and is free to lead the Proteas on Thursday in the third test against Australia in Adelaide.
Crisis-torn Australia have made six changes in a bid to stop an unprecedented series clean sweep by South Africa in the day-night test.
