The SABH issued a statement on Monday describing the incident as "an uncivilised act directed against the interests of the Republic of Croatia and a gauntlet thrown to the politics of the Government of Mr Ivo Sanader".
"Neofascist reactionaries should be stopped with effective and unequivocal political and police action as it is done in other European countries," the statement said.
The IDS said in a statement it was "appalled by the violence as an antidemocratic and uncivilised act directed at the very heart of the constitutional system of Croatia", adding that it was concerned that this act might spark a new series of attacks on antifascist monuments.
The party demanded that the relevant authorities take all the necessary legal measures to find "the perpetrators of this terrorist act" and called on all citizens to condemn the act.