Bulldogs coach Dean Pay.

Bulldogs coach Dean Pay has been hit with a $25,000 breach notice after the NRL deemed his post-match spray at the officiating in Thursday's loss to Brisbane an attack on the referees' integrity.

A fuming Pay described several contentious calls as "ridiculous" and "disgraceful" in the wake of the Canterbury's 22-20 defeat to the Broncos, with his comment "it's like we're not supposed to win" in particular crossing the line.

The Bulldogs are considering whether to appeal the proposed fine, with five business days to respond to the breach notice.

"The club is currently reviewing the contents of the breach notice and will consider the appropriate action to take in the next few days," a Bulldogs statement letter to members on Tuesday morning read.

After Pay made specific complaints about Moses Mbye's game-turning sin-binning and a controversial ruling on a Jamayne Issako fumble, referees boss Bernard Sutton rang the rookie coach to explain the officials' interpretations.

Sutton defended the decisions as the correct calls by both lead referee Gerard Sutton and senior review official Steve Chiddy.

In an NRL media release, Head of Football Brian Canavan said "the comments reflected on the integrity and performance of the match officials and went beyond the acceptable parameters".

Addressing the media on Tuesday, Mbye conceded that his 79th-minute penalty had been correctly awarded by the letter of the law, and stressed that his and the club's focus has now turned to Friday's high stakes clash with Parramatta.

"The rules state that you're not allowed to [make] contact when he's contesting the ball and I brushed past him, just brushed over his shoulder," Mbye said.

"I think he just felt it. At the end of the day that's the rules and there had to be some sort of outcome and that's the one it was.

"It's tough, it's a contact sport but unfortunately he didn't have the ball at the time and I made contact with his shoulder lightly, and I found myself walking off early.

"But we can't get too bogged down in it, if we keep dwelling on it and going back to whether they got the call right or wrong it's just going to burn up too much energy."

Pay and the Bulldogs will now have five business days to respond to the notice, as per NRL protocol.

He is the first coach to be fined by the NRL the season for comments around refereeing in a season when a highly-publicised crackdown has seen penalty counts balloon at times over the first nine rounds.