The protest note refers to locations in the basin of the River Sutla that belong beyond any dispute to the Croatian municipalities Novi Dvor Klanjecki, Miljana and Klanjec, the ministry said.
The note forwarded to Slovenia's embassy in Zagreb reiterates Croatia's demand that the razor-wire fence on Croatia's territory must be removed without delay.
Croatia warns that Slovenia's conduct is in contravention of assurances given by Slovenia's top officials on 29 November, that no such fence would be set up in the areas that might be considered disputable considering the two countries' border demarcation efforts.
Zagreb refutes Ljubljana's explanation that erecting the fence is a temporary measure that does not prejudge the border demarcation solutions.
Slovenia's conduct has been provoking situations which are the reason why Croatia is sending protest notes for four weeks in a row, the Croatian ministry recalls.
Croatia also hopes that Slovenia will respond to its justified protests and that Ljubljana will cease putting up barbed wire on Croatian territory in the spirit of European and good-neighbourly relations.