Police were called to a sci-fi convention after a confrontation between costumed characters from rival clubs.
Trouble flared when members of the Norwich Sci-Fi Club were refused entry to a fair hosted by the Norwich Star Wars Club at the University of East Anglia.
More than a dozen sci-fi fans from both groups, including some in fancy dress, were involved in the confrontation on Sunday after a member of the Norwich Sci-Fi Club attempted to get an autograph from Doctor Who actor Graham Cole.
It is understood the two groups had been involved in a long-running dispute and the hosts had warned their rivals to stay away after comments were posted on Facebook.
Norfolk Police confirmed that they had been called to reports of an assault.
A force spokesman added: "After lengthy investigation, talking to witnesses and reviewing good CCTV footage, it was confirmed that there was no assault.
"The two rival groups were spoken to and advised to keep out of each other's way."
Both groups told the Norwich Evening News that they now hoped to put their differences behind them.