Bruins Ryder Roberts scored two goals while Garrett Danner made 11 saves in the cage.
A total of eight Bruins (seven players and one coach) are in Szombathely, Hungary.
The Americans were led by two goals each from Danny McClintick, Paul Reynolds and Chris Fahlsing.
The 2013 FINA World Championships will be held July 22-August 3 in Barcelona, Spain.
The Americans advance to tomorrow's fifth-place game against Japan.
Paul Reynolds and Danny McClintick each scored two goals for Team USA.
Seven Bruins were named to the men's squad while five will represent the USA on the women's team.
Attacker Daniel Lenhart led the Americans with two goals in the fourth period.
Lucas Reynolds leads the Americans with five goals on five shots.
Serbia scores four unanswered goals in the fourth quarter to pull away from the Americans.
Paul Reynolds and Jack Fellner each scored a hat trick for the Americans.
Paul Reynolds led the Americans with two goals late in the fourth period.