"If people want to come out over this weekend and start ripping into the referees, I've got some advice for them: they better start ripping into me first because all the referees are doing is following instruction," Greenberg said on Triple M radio.
The NRL has been open about its edict to clean up the play-the-ball as well to ensure sides remain on side in defence.
Greenberg said it was up to the referees to ensure their crackdown lasts the entire season.
"I've asked the referees to make sure it doesn't just happen in rounds one, two and three, that it happens all year," he said.
"Ultimately, it'll ensure that the fans have a much greater game to watch."
Greenberg also said the competition committee would consider the reintroduction of the five-minute sin bin to prevent teams deliberately conceding penalties close to their tryline.
Johns believed the game was being destroyed by penalties.
"Twelve penalties blown in that first half, I'd say nearly three-quarters of them for offside, inside the 10," he said during the Nine Network's game commentary.
"Rugby league's a game that flows and there's attrition. You can't do that with so many penalties.
"There's no flow.''
- AAP
