The violent clashes on August 25 led to 64 arrests and the stabbing of a Millwall fan outside Upton Park, and there were pitch invasions during the match.
Related ArticlesAston Villa v West Ham United: previewCagliari president eyes West HamWest Ham found guilty of crowd violenceFernandes favourite to take over West HamWest Ham eye end of Icelandic liftSport on televisionWest Ham were found guilty of two charges: failure to ensure their supporters refrained from violent, threatening, obscene and provocative behaviour, and failure to ensure their supporters did not enter the field of play.
The club were cleared of the more serious allegations of racist abuse and missile throwing during last week's three-day hearing.
The FA confirmed the penalty after reconvening this morning to hear and consider West Ham's plea of mitigation.
The club have 14 days to appeal the decision upon receipt of the commission's full written judgement.