Welwyn Garden City say Watford’s decision to withdraw from a friendly at late notice is an example of “clubs at the elite level having no interest in the way grassroots clubs function”.
Watford were due to send their under-23s to the non-league club on Saturday.
Welwyn Garden City claim Watford told them at 14:00 BST on Friday – one day before it was due to take place – they could not field a side.
“We’re sad, disappointed and angry,” said a Welwyn Garden City statement.
The statement added: “Watford FC have conducted themselves in such a poor manner and with such naivety as to what this means for Welwyn Garden City FC.
“Everyone at WGC FC feel completely let down.”
Welwyn Garden City, who play in the Southern League Division One Central, were hoping for a crowd of up to 400 for the match.
The part-time club said they had paid for match officials, hospitality and programmes for the game.
Meanwhile, a Watford side beat West Ham’s Under-23s 2-1 in a behind-closed-doors friendly on Friday afternoon.
Watford’s first team are due to play a friendly against Serie A side Sampdoria on Saturday at Vicarage Road.
A statue of Graham Taylor, Watford’s former manager who died in January 2017, will be unveiled before the game.
Watford fan Stuart Levy tweeted about the Welwyn Garden City postponement: “On the face of it, extremely poor form this. Ironic that this has occurred when we celebrate all things GT and this is the last thing he would ever of allowed to happen.”
The BBC has contacted Watford for a comment but is yet to receive a reply.