1) By definition, noise is considered a public-health and environmental problem and challenge. Noise protection is required to be carried out by government bodies, local and regional governments, as well as legal and natural persons engaged in registered activities (Article 4, Noise Protection Act).
2) You can call the competent Sanitary Inspectorate which is authorised to measure noise (the exceeding level of noise coming from the reported object is measured, according to the limits prescribed by the Noise Protection Act and the Ordinance on maximum permissible noise levels in areas where people work and live).
3) Call the competent police department, which is responsible for the submission of indictments for offenses in the area of the Noise Protection Act. Environmental noise is, under this act, described as any unwanted harmful sound towards human health and the environment in outer spaces caused by human activities, including noise emitted by: means of transport, road transport, railway transport, air transport, maritime and inland waterway transport as well as facilities and procedures for which, under special regulations in the field of environmental protection, there is a need to obtain a decision on integrated environmental protection requirements or a decision on environmental acceptability (art. 2, Noise Protection Act).
4) According to the Act on Offenses against Public Order, actions falling into the category of "offense" are those that illegally disturb the peace, work or normal life of citizens, creates restlessness, moodiness, anxiety and so on. One of the basic elements of this offense is the concept of public places as a scene for the offense. The definition of public places seems to be dependent to greater or lesser possibilities of access to the public, and following this approach, public spaces are divided into real and fictitious. The real ones are those that by its function are intended for the public, and the fictitious ones those which are not public places by its function, but under certain circumstances, the actions and the consequences of offenses committed in these places are reflected towards the public. Thus, home or other personal space can also be a fictitious public. Furthermore, municipalities and cities in the Republic of Croatia have the power to make their own decisions to sanction similar behaviour, including shouting, noise, banging, loud music and other disruptions of house rules in residential buildings. Such regulation, if adopted, should be published in the official gazette of the local government unit. (http://www.mup.hr/1166.aspx)
The proposal is: if you feel that the noise has the characteristics of disturbance of public peace and order, request police intervention, or, if you believe exceeding noise levels are present (under the Noise Protection Act), seek the assistance of a competent sanitary inspection.