The move came after last week's proposal by the Slovene government for Slovenia to proclaim an ecological zone in the Adriatic.
"The problem of demarcation of the border with Slovenia should be resolved through international arbitration, which the DC has always seen as the only proper instrument for resolving the issue," the party's secretary for international affairs, Radovan Fuchs, said at a press conference in Zagreb.
Fuchs said that by then the two countries should refrain from taking unilateral steps or provoking incidents as agreed by their respective governments at a meeting on the northern Croatian Adriatic islands of Brijuni.
DC president Vesna Skare Ozbolt, who also serves as minister of justice in the present government, said that proclamation of an economic zone would mean nothing unless a control and protection system was established.
She added that her party would propose a Coastal Guard Bill which would enable systematic control of the Croatian part of the Adriatic, which stretches from the Prevlaka peninsula in the south to town of Savudrija in the north.