The fine was levied for no Vietnamese players participating in a press conference before the opening match of the ongoing AFF Suzuki Cup against Laos on November 8 in Vientaine.
"If Vietnam continues to relapse, the penalty will be heavier," the AFF said in a statement sent to VFF last Wednesday.
Under the rules of AFF, the head coach and a starting player from each football team are obliged to show up at the pre-match press conference to be held at least one day prior to the match.
However, only Coach Park Hang-seo and his language assistant attended the press meet on November 7.
Vietnamese players have showed up at the subsequent three press conferences before matches against Malaysia, Myanmar and Cambodia during the group stage.
The Indonesian Football Association was fined $8,000 for violating regulations on advertisements.
Cambodian player Bin Chanthachery was fined $1,000 for receiving a red card in the match against Myanmar.
Earlier, VFF was fined $12,500 for letting Vietnamese fans burn flares during the Asiad 2018 semifinal match.
Le Hoai Anh, general secretary of VFF, had said he hoped such incidents will be not repeated at upcoming international matches, especially the 2018 AFF Suzuki Cup.
Vietnam has secured top group spot in the AFF Cup to enter the semifinals with a 3-0 win over Cambodia on home ground at Hang Day Stadium in Hanoi Saturday night.
Vietnam’s semifinal match will be played on December 2.
Rewatch highlights from Vietnam vs Cambodia match here: