Australia batsman David Warner defended Steve Smith after the captain was fined for umpire dissent in the second Test against New Zealand.
Smith was fined 30 per cent of his match fee following an unsuccessful review on day four of the Test, which Australia won comfortably.
He called for a review of an lbw decision that went Kane Williamson's way, but the third umpire ruled the New Zealand batsman had hit Josh Hazlewood's delivery before it struck his pad.
On his return to Sydney on Thursday, Warner said Smith was unhappy with the decision not to use Snicko after HotSpot.
"When you're on the field that's not communicated to you, so that's why he might have stepped across the line a little bit," he said.
"He didn't know that until he came off the field. If he had his time again and he knew that he wouldn't have debated that with the umpire.
"There has been a bit of talk about the team and the aggressive brand of cricket that we play. Steve spoke about not trying to cross that line."
Australia claimed a seven-wicket win in Christchurch to complete a 2-0 series win and take the number one Test ranking.
They hold the top ranking in the five-day format and one-day internationals and Warner said there was more to come.
"Our sole focus was to be number one in Test cricket and one-day cricket, obviously Twenty20 will really cap it off for us," he said.
"But we've got to really work hard to achieve that goal, but at the moment we're really, really happy with where we are."