"I didn't think of it before the series, but I did hear that yesterday. It's probably a little bit smart, being like that," du Plessis said in Port Elizabeth.
"If you can entice someone to make a mistake, to get them missing the rest of the series - that's probably a tactical move.
"Before we came into this series and I looked at all the demerit points - all of it was on the South African's team side. There wasn't much on the Australian team.
"Now that it's happened, it's possibly an angle we can look to get to."
Steve Smith backed Warner to handle any additional pressure created by the hosts.
"Davey plays really well when he's aggressive and gets into a contest. Obviously, he's going to have to be careful not to cross the line," Smith said.
"He's not got any more chances. He's aware of that."
Du Plessis chattered about Warner when the aggressive opener was batting on day three of the first Test, imploring teammates to feed off the batsman's "ego".
Warner's innings ended soon after when he played a loose stroke to Kagiso Rabada, eliciting a send-off from the speedster that caught the attention of both umpires.
Du Plessis suggested on Thursday that words were not a particularly effective weapon in cricket.
"For me, it's probably more about your presence as a player than the stuff that comes out of your mouth," he said.
"As a captain, we don't look to push that line. We don't look to find the grey areas."
Smith had suggested last month his side might look to niggle Rabada, who is also facing a suspension if he misbehaves.
Rabada has five demerit points on his record, while du Plessis has three. Tim Paine and Nathan Lyon have one point each.
-AAP
