The parliamentary party's secretary-general, Pero Coric, said in a press release on Friday night that Nikolic's interview was not the kind of political interview 21st century European leaders should be giving.
He said "we haven't heard such statements since the death of Slobodan Milosevic and the arrest of (Nikolic's) political mentor Vojislav Seselj."
Coric said "Vukovar was a symbol of the survival and the wish of the Croatian people for its independence and sovereignty, and a heroic city which was and always will be Croatian."
The party condemned Nikolic's statement in the strongest terms and demanded that Croatia's authorities consider sending a diplomatic note and ask Nikolic to apologise.