Steve Smith believes Kagiso Rabada's reprieve has created a new standard on physical contact in cricket, with Australia's skipper struggling to hide his concern about the International Cricket Council's judicial process.

Smith has aired a series of grievances on the eve of the third Test in Cape Town, where South Africa's spearhead Rabada is free to play after his fifth charge in the space of 13 months was downgraded upon appeal.

Rabada brushed Smith's shoulder during a screaming send-off that marred the second Test, earning himself a two-Test ban after grabbing man-of-the-match figures of 11-150.

Match referee Jeff Crowe, a former New Zealand captain who has overseen international matches since 2004, found the repeat offender had a chance to avoid contact and there was no, "evidence to support the argument that the contact was accidental".

Independent commissioner Michael Heron, a New Zealand QC, overturned that verdict and noted he was "not comfortably satisfied that Mr Rabada intended to make contact".

Kagiso Rabada has been South Africa's best bowled through the first two Tests. ( AP: Themba Hadebe )

The ICC, having espoused a zero-tolerance approach to physical contact in recent years, rubber stamped the ruling.

"The ICC have set the standard, haven't they? There was clearly contact," a stunned Smith told reporters.

"He bumped me a little bit harder than it actually looked on the footage.

"They've deemed the contact not to be deliberate and set the line in the sand of what is appropriate and what's not."

Smith found it "pretty interesting" he had zero input at the six-hour hearing into Rabada's send-off, during which team manager Mohammed Moosajee was among a handful of South African witnesses.

"The other person involved [is] not getting asked about it," he said.

Smith also fired back at an inflammatory message posted on Vernon Philander's supposedly hacked Twitter account, in which it was suggested the batsman exaggerated contact and "gave KG the shoulder".

"That was a bit over the top … that's all a load of garbage," he said.

Smith is yet to make a ton this series. ( Reuters: Rogan Ward )

Smith's comments are sure to create even more bad blood between the rivals at Newlands, where the series continues on Thursday.

Both camps have vowed to continue verbal niggling in a series locked at 1-1, but Smith downplayed the prospect of Australia trying to push the boundaries further in light of Heron's leniency.

Andy Pycroft, who will oversee the rest of the series, has already made his expectations clear.

"He wanted to have a chat to the senior players: myself, Davey [Warner] and Nathan Lyon," Smith said.

There have been plenty of contentious moments throughout this series so far. ( AP: Themba Hadebe )

"I think he's going to chat to [South African captain] Faf [du Plessis], AB [de Villiers] and Hashim [Amla] as well. Just to ensure that the series continues to be played in pretty good spirit.

"I certainly won't be telling my bowlers to, 'Go out there and after you take a wicket, go and get in their space'. I don't think that is on.

"What's the point of over-celebrating and getting in the face of a batter? You've already won the battle."

Smith felt for Crowe, who is among the sport's most respected officials.

"The way he handled both sides … he did a terrific job, I'd be feeling a bit annoyed if I was him," he said.

AAP