Penrith Panthers winger Brent Naden was allegedly the subject of racial abuse from members of the crowd during his side's 18-12 victory over New Zealand Warriors at Central Coast Stadium.
An Indigenous Australian, Naden reported comments made by a small section of fans to a member of Penrith's training staff, who then passed on the information to police.
Footage broadcast by Fox Sports showed a group being spoken to by officials before they were escorted from the venue.
The NRL is investigating the incident, with acting CEO Andrew Abdo declaring the governing body will take "decisive action" against anyone found guilty, as well as offering support to those players involved.
"Racism and vilification will not be tolerated in our game," he said.
"Bringing communities and cultures together is part of rugby league. We pride ourselves on being inclusive and taking a leadership role in driving social change.
"Any fan found to have racially abused a player or another fan will not be welcome at our games.
"We have shown in the past that we will take the strongest possible action to ensure fans guilty of racial abuse are banned from attending the Telstra Premiership.
"We will work closely with NSW Police, stadium authorities and the clubs to determine the facts and take decisive action against anyone guilty of racial abuse."
Naden scored the opening try as table-topping Penrith set a new club record by securing a ninth successive victory.
"He's okay, it's not the first time he's heard that in his life - but I think in this forum it has been," Penrith coach Ivan Cleary told the media after the game.
"He certainly took offence to it at the time but he's okay now.
"It's one of those situations that you can only react how you feel at the time. Whatever was said, it definitely affected him."
Apisai Koroisau and Dylan Edwards also crossed in the first half for the in-form Panthers, while Nathan Cleary kicked six points to help see off the Warriors.