"I sympathise with the Jewish people and their tragedy that must not be ever forgotten. All of us are today responsible for action that will prevent any hate crime or genocide against peoples of another race or religion from ever happening again," Reiner said in his message issued on Thursday.
This year, Yom HaShoah was observed on 5 May.
Members of the Jewish Community in Zagreb as well as the Bet Israel organisation held commemorations in Zagreb and Krapina, with state and local authorities attending the events.
Yom HaShoah or Holocaust Remembrance Day is observed as Israel's day of commemoration for the approximately six million Jews who perished in the Holocaust as a result of the actions carried out by Nazi Germany and its allies. In Israel, it is a national memorial day, which was inaugurated in 1953.