The rally was organised through the Facebook, and one of organisers, student Ivan Loncar, called on the protesters to hold a peaceful and dignified rally.
Ivan Pernar, the organiser of anti-government demonstrations in Zagreb, appeared at the Osijek rally but he was booed by groups of protesters in that eastern city.
About 40 policemen were engaged as the security at the protest.
According to a report by the Osijek police, an underage protester was arrested for having thrown firecrackers, and a window pane at the offices of the Croatian Democratic Union (HDZ) offices was smashed.
Several hundred protestors also rallied in the biggest Croatian Adriatic city of Split on Saturday evening. They marched through the centre of the city and tore a large poster with the image of the former Croatian Prime Minister Ivo Sanader in front of the HDZ offices, which were under the strong police security.
Protesters expressed their opposition to Croatia's prospective admission to the European Union and to Croatia's NATO membership. Apart from the demand that the current government should step down, they also asked for smaller influence of the Catholic Church on the political life, the revocation of the right of Croatian expatriates and the Diaspora to vote in Croatia's elections, and the immediate declaration of the exclusive Croatian economic zone in the sea.
A peaceful anti-government protest was held in the northern town of Koprivnica on Saturday evening with some 400 people attending it.
In the northern coastal city of Rijeka, some 200 people rallied this evening, protesting against the ruling HDZ and the strongest opposition Social Democratic Party (SDP) which is in power in Rijeka.