The NRL has issued Manly with a breach notice, giving them a $10,000 fine for Geoff Toovey's post-match comments about the officiating in the Sea Eagles' loss to South Sydney.

Manly coach Toovey questioned the standard of refereeing in the league after the 22-10 loss on Friday night, in particular citing the decision not to award a try to Steve Matai in the 52nd minute because of inconclusive evidence of grounding.

"I just think today the officials determined the outcome of the game, not the two teams in the middle" Toovey said after the match.

"Aren't we meant to have the best referees for this game. Are they the best referees we have?".

On Monday afternoon the NRL released a statement outlining the breach notice and the fine for Toovey's outburst.

"I accept that emotion is a big part of our game but that is not an excuse for making unwarranted attacks on match officials," the NRL's head of football, Todd Greenberg, said in the statement.

"There needs to be a balance between coach's expressing their opinions and their emotions and showing respect for the game and the match officials in that process."

The league's referees elite performance manager, Daniel Anderson, defended the performance of match officials Shayne Hayne and Henry Perenara.

"The performance of the match officials in a fiercely contested game on Friday night was very good," Anderson said.

"With the Steve Matai ruling, the officials followed the proper procedures in the video review process and arrived at the correct decision.

"The referee on the field ruled the player grounded the ball short and was then held up and there was insufficient video evidence to warrant over-ruling that decision."

Manly will have five working days to make submissions relating to the breach notice.