Steve Smith fined 30 per cent of match fee after Australia beat New Zealand

Australia captain Steve Smith defended his side as "nice guys" despite him being fined 30 per cent of his match fee for dissent following the second Test against New Zealand.

Australia won the Test by seven wickets to move to the top of the world rankings, but celebrations were marred by Smith being hauled before the International Cricket Council match referee to explain his actions amid continuing fallout over umpire abuse.

He was charged with dissent and subsequently fined in connection with the same obscenity-laden rant that cost Josh Hazlewood 15 per cent of his match fee. 

But Smith talked up the Australians as "nice guys" who play the game hard and push the boundaries but don't mean to offend.

The abuse levelled at the umpires during their win in Christchurch was the latest in a string of incidents involving Australia, including in 2013, when then captain Michael Clarke warned England's Jimmy Anderson to prepare for a broken arm.

"I don't think we're not nice guys. We play a good, hard, aggressive brand of cricket," Smith said, admitting he and Hazlewood were wrong in how they approached the umpires after Australia were denied an lbw decision against Kane Williamson.

"For us it's about knowing where that line is and myself and Josh Hazlewood have crossed that line in this Test match and that's not what we're about and hopefully we can learn from that and continue to develop as a team and get better."

Smith said he believed at the time he was acting correctly to question the umpire's decision.

"I thought I was well within my rights to go up to the umpire and ask him why we didn't use the real time snicko," he said referring to the technology used to determine if the ball had hit the bat.

"That's deemed to be dissent and I'll cop that on the chin and I need to be better as a leader, I need to set the example and that was not good enough.

"For me it's about trying to learn from my mistakes and improve and try and get this team going forward in the right direction and playing the good aggressive brand of cricket that we play so well and know there's a line there that we can't cross."

Despite the on-field dissent, New Zealand captain Brendon McCullum, who retired from international cricket at the end of the Test, maintained there was a good relationship between the two sides.

"This series has been played in great spirits, I think, and the one back in Australia. I think Steve Smith has been a catalyst for that," he said.

"He plays the game for the right reasons as well. He plays with his heart on his sleeve but he's a very respectful guy and a wonderful cricketer.

"They're number one in the world now and a lot of that is to do with his leadership and [Australian coach] Darren Lehmann's as well."