The Amsterdam outfit's supporters unfurled an offensive banner aimed at Champions League Group H opponents Celtic on November 6 and the club has been fined 25,000 Euros.
The Dutch side beat the Scottish champions 1-0 November 6 to leapfrog them into third place in Group H, with midfielder Lasse Schone netting the only goal of the game.
However, the defending Eredivisie champions have been hit with the sanction after the governing body found that their supporters had been guilty of improper conduct by unfurling the banner at the Amsterdam Arena.
"Ajax has been fined by UEFA after a banner appeared on the stands of the Amsterdam ArenA during the match against Celtic FC," a statement on the Ajax website read. "The banner was aimed at Ajax's opponents that night. UEFA imposed a fine of 25,000 Euros. The possible penalty for such an offense is a fine of 50,000 Euros plus the closure of some parts of the stadium at the next European home game.
"After a prompt and adequate response from Ajax the fine was halved and the partial closure averted. The penalty will be recovered from those responsible."
Ajax could be punished further following crowd trouble during its visit to Celtic on October 22 and another disciplinary hearing is set to take place, with a ruling expected November 21.