"Hungary must have real border protections at the Croatia border," Orban said during a news conference in Vienna, aired by Euronews.
Orban argued that the Croatian proposal to remove the fence and build a transit corridor for refugees traveling to Austria and Germany contradicted previous agreements.
Earlier this month, Hungary finished the construction of a 108-mile fence on the southern border with Serbia and announced a plan to extend the fence to its border with Croatia to control the surging influx of undocumented migrants.
Hungary to Seal Croatian Border After Completing First Fence Line
Hungary will shut its border with Croatia as soon as the first line of the barbed-wire fence it is erecting is completed, Viktor Orban said.
"On the Croatian border, we will build one fence line and immediately start building another line. But we will not wait until the second line is complete to announce the lockup."
Before sealing the border, Orban said he plans to make several state trips to explain "the situation we are in." "Only then will we be able to close the border," the prime minister added.
Hungary, which is in the EU's Schengen borderless area, was a key transit country for tens of thousands of migrants traveling to prosperous Western Europe. The country tightened controls on its Serbian border in early September, forcing refugees to seek alternative routes through Croatia and Romania.