Wakefield Trinity Wildcats have been fined £1,000 after fans threw smoke bombs onto the pitch during their match at Castleford Tigers.
The incident disrupted play during the game at the Mend-A-Hose Jungle stadium on Sunday, February 8.
The club was found guilty of conduct prejudicial to the interests of the game and misconduct of spectators.
The fine has been suspended until the end of the 2015 season.
Wildcats chairman Michael Carter said: “We would like to thank the rugby league for undertaking a thorough investigation and recognising the actions of the club to identify and punish the indiscretion.
“The club is committed to the safety of all rugby league fans and will continue to be a family focus club.
“Obviously I am annoyed that we have been fined due to the actions of mindless idiots. They are not welcome at any of our games. But equally, I don’t want this to besmirch the good name of the majority of 2,000 fans that travelled that day.
“As a club we will not tolerate actions of this nature and if the culprits are proved they will be banned from attending our games.”