Hasler has become the second coach this season to receive an official final warning from the league after North Queensland boss Todd Payten last month.
"Mr Hasler has been reminded of his obligations under the NRL Rules and Code of Conduct as well as his general responsibility as a sporting leader," read a statement from the NRL.
"Negative public remarks about match officials significantly hinder the recruitment and retention of match officials at the community and pathways tiers of the game.
"All rugby league participants are reminded to respect match officials who perform a vital role within the game."
Asked about his comments ahead of Saturday's clash with Brisbane, Hasler said: "I was just pointing out a few things."
Hasler was frustrated with a pivotal decision in the second half of his side's 28-16 loss to Melbourne last week and promised then to seek clarification from the NRL.
Titans hooker Sam Verrills was denied a try on the grounds he had made contact with his teammate Tino Fa'asuamaleaui as he attempted to burrow past Melbourne defenders lying in the ruck.
Bunker official Kasey Badger ruled Storm fullback Ryan Papenhuyzen had been denied the chance to tackle Verrills because of this contact, with the Storm scoring their match-sealing try minutes later.
"Kasey got it wrong, again," Hasler said then of the call.
"There's an email from the NRL about players lying in the ruck; that's fine, let them lie in the ruck, but you shouldn't lose the advantage.
"They were lying all over the ground and six again, penalty, I don't know whether it was called, and young Vez (Verrills) picks up the ball and dives through, doesn't touch anyone, (Storm fullback Ryan) Papenhuyzen wasn't obstructed.
"That was the word-for-word what the NRL sent out so I'll be interested to see what their explanation was."
It is not the first time Hasler has critiqued the match officials since joining the Titans last season.
The two-time premiership winning coach said in April the liberal use of the sin bin was "spoiling" the game and calling for a return to the two-referee system.
Hasler also called Badger's officiating of a loss to Canberra "pretty poor" last season.
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