Melbourne United recruit Isaac Humphries has been fined $1500 by the NBL for labelling the league's referees "not great" in a radio interview following the pre-season Blitz tournament.

The NBL said Humphries, who will have $500 of his fine suspended, had breached the league's code of conduct.

The centre's outburst came after he was asked on SEN radio whether the competition's referees officiate the league's big men differently from their smaller counterparts.

"I've played in the NBL for a few years now, and look the NBL refs are ... I don't want to talk bad on them, but they're not great," Humphries said on Wednesday.

"But it's all good. We just have to all deal with that.

"They're doing their thing and we can't let that get in the way of our progress.

"We all know what they are like. I hope they are trying to get better, as we all are."

Humphries will be free to line up in United's first game of the NBL season against the New Zealand Breakers on Sunday.

In his first year at the club, the former Adelaide 36er is set to take on more work following a season-ending achilles injury for United's other big option, Ariel Hukporti.