Clashes broke out between Croatian police and anti-EU demonstrators one day ahead of a referendum that will decide the country's membership in the bloc.
A protester had tried to take down the EU flag flying in a square in the capital.
Five people were arrested.
The "No" camp has played on fears of a wave of foreigners buying up Croatian companies and property.
Others say the timing is wrong and that the EU is not what it once was given the debt crisis that is threatening the single currency.
Some government officials warn a no vote would bring down the country's credit rating and deter investors.
Leaders of the small Adriatic country have said there is no better option despite the economic turmoil in the EU.
The latest opinion poll released on Saturday suggests the vote will pass, with support at 61 percent.
The Croatian foreign minister echoed these findings.
(SOUNDBITE) (Croatian) CROATIAN FOREIGN MINISTER VESNA PUSIC SAYING:
"According to all indicators and all opinion polls, a majority of citizens is for a European Croatia and the security this environment provides. This is why it is important that as many people as possible go to the polls so that the true will of the citizens could be seen in the referendum results."
Not everyone was convinced it was the right move for the country.
(SOUNDBITE) (Croatian) THIRD MAN SAYING: "I will vote no, no." (Reporter asking why?) "Because they did not bother to explain to us ordinary people what this EU really stands for. My opinion is that it means nothing good. EU is just a platitude."
If the referendum passes, EU member states must ratify Croatia's accession before it can join, which would make the nation its 28th member.
Marie-Claire Fennessy, Reuters