The NRL are set to launch an investigation into the racial abuse of Roosters star Latrell Mitchell on social media, as reported by NRL.com.
Mitchell was one of many players attacked on social media over the weekend, and it is understood that if the culprit is is identified as a club member, could have their membership revoked and be banned from attending NRL games.
"Racism must be called out in all its forms because the standard you walk past is the standard you accept," Greenberg told NRL.com.
"I commend Latrell for doing just that. These comments are disgusting and have no place in our game.
"What I love about rugby league is the diverse cultures and backgrounds it brings together. The heritage of our players is what makes our game so special.
"Incidents like this show why our school programs like In League In Harmony and Indigenous rounds are so important to educate the next generation about inclusion.
"There is no place for any sort of abuse on social media towards our players or their families."