Leaflets called on citizens not to vote for presidential candidate Stjepan Mesic, whom they dubbed a "Serb son-in-law".
The association calling itself the Templars labelled Mesic's voters as "an aggressive minority of far-leftists, faithless, autonomists, citizens of the Serb, Bosniak and other minorities who gathered to wholeheartedly support the Serb son-in-law Mesic".
Pupovac told the press the leaflets represented an attempt to spread fear and stop people from going to the polls on Sunday.
He said the leaflets attacked the fundamental constitutional, democratic and ecumenical values of the state and the role of the Croatian president.
Pupovac said he was surprised that only misdemeanour charges were filed against the perpetrators. He added criminal charges should have been pressed because the leaflets undermined the regularity of presidential elections and spread inter-religious and inter-ethnic intolerance.
Pupovac said the leaflets were the result of the end of the presidential race, which he added focused more on the war and war divisions than on peace and the strengthening of civil institutions and confidence in Croatia.