Warriors called off the game, without consulting Widnes, as the pitch had deteriorated following Storm Doris and needed time to recover so that Wigan Athletic could play football on it.
But the match then went ahead on the scheduled date at the Vikings' ground.
Warriors, who won the game 28-26, must pay £2,000 in costs for the RFL.
An independent operational Rules Tribunal determined the Warriors breached operational rules and some of the league's code of conduct.
The Rugby Football League said it would set up a working party so the stadium sharing clubs - Wigan, Hull FC, Salford Red Devils and Leeds Rhinos - can discuss the issues in relation to sharing a ground.
Wigan Warriors have been reprimanded and ordered to pay costs for postponing their Super League fixture against Widnes Vikings in February.