A notorious section of the Bulldogs' Army has drawn fire from the Canberra captain Simon Woolford and Cronulla counterpart David Peachey after both men were targets of abuse in recent matches against the premiership favourites.
Woolford had beer thrown over him while leaving the Sydney Showground two weeks ago while last Saturday Peachey was struck by two bottles at Toyota Park after scoring a try.
Vagana, who heads to Cronulla next season, implored the fans to control their emotions during the finals' series.
"Every club has it's bad apples but we seem to have a bit more than everyone else. It's a concern for rugby league."
Vagana said the supporters had been generally well-behaved this season but the tension is increasing now the NRL trophy is within sight.
"We got booted last year so they've been waiting for two years for the final and they're a bit edgy. It's a shame someone like Peachey who's played for 10 years has to take rubbish like that.
"At the end of the day it's just a game."
When crowd trouble peaked at Bulldogs' games two years ago, high-profile players Hazem El Masri and captain Steve Price appealed for calm through a series of advertisements.
It was not known if a similar plan of action has been contemplated this year.
The NRL are currently co-ordinating security arrangements with the Bulldogs management.
Peachey, who predicts the Bulldogs will win next month's grand final, has urged the club to clamp down of rowdy fans.
"These fans appear to play up every week yet nothing is done about it. It's time for the Bulldogs officials to take a stance before it's too late and someone gets hurt.
"I'm disappointed for the Bulldogs' players because they could be the ones that suffer because of a small number of their fans.
"If they act like this on grand final day it could leave a really bad taste."
Aggressive behaviour has already switched some supporters off watching their team.
One fan who "bleeds blue and white" told the latest edition of Rugby League Week magazine he preferred to watch the games on television.
"I'm not prepared to witness the violence and be seen as one of these trouble-making supporters," he said.
"I have seen people harassed. I can't put up with the verbal and physical abuse that is dished out by some sections of the Bulldogs supporter base."
The Warriors have not played against the Bulldogs in Sydney since 2000 because the Australians decided to hold their home games in Wellington.
Saturday's game is expected to sell out with almost all the 20,000 tickets sold.