Fast bowler Josh Hazlewood, who unleashed a profanity-laden barrage at the umpires after an lbw appeal was turned down, pleaded guilty to a similar charge yesterday and was fined 15 percent of his match fee.
The International Cricket Council was expected to announced Smith's penalty later today.
"I need to be better as a leader. That was not acceptable behaviour," Smith said.
He added that he believed his charge related to questioning the umpires about the technology used when checking the lbw appeal against New Zealand batsman Kane Williamson.