The French club were punished by an RFL operational rules tribunal after their supporters verbally abused and intimidated match officials following a 22-21 Super League defeat by Hull KR in Toulouse on June 22.
A statement from the RFL said the Dragons were guilty of "conduct prejudicial to the interests of the game" and breached the game's Respect Policy.
A spokesman added: "The charges were brought after the club failed to provide information to the investigation into the incident.
"In finding the club guilty of misconduct, the tribunal ruled that £1,000 be payable within 28 days and a further £1,000 be suspended until the end of the 2014 season."
The Catalan club were fined £1,000 in September after being found guilty of improper conduct.
Chairman Bernard Guasch and coach Laurent Frayssinous were also fined £500 at the same time, £250 of which was suspended until the end of 2014, for publicly questioning the integrity of the disciplinary process following the suspension of Zeb Taia.