According to reports, police were called to Erskineville Oval last Saturday after a fight broke out during a pre-season under-19s match between South Sydney and the Sea Eagles.
A NSWRL investigation found that former player Henry Alesi, who is unregistered, sparked a physical incident after "acting aggressively" towards another spectator, Manly Jersey Flegg squad member Siua Fotu.
Sea Eagles SG Ball player James Malau'ulu, who played in the match, ran from the bench to the fence where the altercation took place and became verbally involved.
While the Manly players escaped NSWRL sanction, the club took action by formally reprimanding Fotu, who didn't provoke the situation, and suspending Malau'ulu until round three of the SG Ball competition.
A NSWRL statement said Alesi would be banned from registering to play in NSWRL competitions until October 31.
Hopoate, meanwhile, is also alleged to have breached the code of conduct for entering the field of play without authority. He was reportedly involved in a verbal exchange.
Alesi and Hopoate have 14 days to respond to the breach notices.
"The NSWRL treats these types of incidents very seriously and has a zero tolerance policy for behaviour that threatens the safety of participants, officials and spectators," NSWRL chief executive said David Trodden said.
"Incidents like these are contrary to the standards of any community sport and do not have a place in our game.
"Everyone who attends our games, in whatever capacity, should be able to do so with the expectation that they are in a safe and enjoyable environment."
Manly released a statement condemning the incident.
"It is a privilege to play the game of rugby league and it comes with the obligation of maintaining appropriate standards of behaviour," Sea Eagles boss Stephen Humphreys said.
"We will continue to work with all of our players and remind them of their responsibilities in meeting the expected standards, even when they are confronted with difficult circumstances."
