Sydney Roosters coach Trent Robinson says referees deciding whether to sin bin players or put them on report for a high shot depending on how their opponent reacts, will only encourage simulation.

Robinson was left bemused after an incident in the first half of his team's thrilling 35-34 win over Gold Coast on Saturday where Titans co-captain Kevin Proctor caught Joseph Manu high.

Manu jumped straight to his feet after the tackle and while Proctor was penalised and placed on report, he didn't get sin-binned.

Robinson said referee Ben Cummins saying on-field the fact Manu hadn't stayed down played a role in Proctor's level of punishment sent a mixed message to the game's players.

"We don't want our players to lie down, and then the commentating around it from referees is 'oh no, they've stood up, they've stood up, I'm OK with that'," Robinson said.

"So what they're saying is lie down."

Roosters player Ben Marschke did get sin-binned in the second-half after catching Jamal Fogarty in the head with his elbow, a decision which led to three Titans tries as the hosts nearly pulled off a remarkable comeback.

Robinson was fine with Marschke's sin-binning but it only added to his frustration about Proctor's punishment.

"That was a silly challenge from Benny ... but the one on Joey Manu, what do you want us to lie down? The NRL's put it back on this gamesmanship or the gentleman's agreement, just don't encourage it," he said.

"It's not our game."

Robinson also believed the decision to place Isaac Liu on report for a crusher tackle on Tino Fa'asuamaleaui was influenced by the Titans forward's reaction.

"Guy stays down, holds his neck. That was ridiculous," Robinson said.

"They've still got a bit to go to work it out.

"It looks like they've calibrated a bit better but we're still not seeing the way that we want to play the game."