Legia supporters had been given 1,000 tickets for the game, after their allocation had been cut from 1,700 on police advice. Another 1,000 supporters had been expected to turn up at Villa Park without tickets.
Legia issued a statement on their official website that accused Villa of refusing to allocate tickets.
It read: “Aston Villa FC is refusing to allocate tickets to away fans in accordance with UEFA regulations for a UEFA Europa Conference League match.”
Legia fans were banned from their match at Zrinjski Mosta earlier in the competition after crowd trouble against AZ Alkmaar.