AZ Alkmaar have been fined 80,000 euros (£68,670) for the behaviour of their fans at their Europa Conference League semi-final second leg match against West Ham in May.
The Hammers, who won 3-1 on aggregate, went on to win the tournament.
During that game at the AFAS Stadion in the Netherlands, AZ fans attacked an area in which West Ham players’ friends and family were seated.
Players tried to intervene to protect their family members.
Michail Antonio and Said Benrahma were among those who tried to step in, moments after the Premier League team had reached the final.
The Dutch club gave stadium bans to 43 fans, and several arrests were made after an appeal was made on television.
AZ, who are in the Europa Conference League again this season, have been ordered to play one Uefa match behind closed doors, although that sanction has been suspended for two years.
Their fine has been broken down as £6,115 for throwing of objects, £12,870 for lighting fireworks, £6,867 for blocking public passageways and £42,918 for crowd disturbances and failure to ensure that spectators cannot move from one sector to another.