German Foreign Minister Sigmar Gabriel is due to begin a two-day tour of Serbia and Kosovo on April 12 to discuss growing tensions between the two sides.
"We see that some wounds of the past still run deep and still keep the tensions up," Gabriel said before leaving for Belgrade.
Gabriel said he would voice "support for democratic development and rule of law" in all countries of the region.
Predominantly ethnic-Albanian Kosovo broke away from Serbia in a 1998-99 war and declared independence in 2008. It is recognized by 114 nations, but not by Belgrade.
Tensions are still high, both between Serbia and Kosovo and between the ethnic Serb minority and central authorities within Kosovo.
Serbia is now an EU candidate, while Kosovo is a prospective candidate. Albania, which Gabriel is to visit on April 16, and Macedonia are also candidates, while Bosnia-Herzegovina is another prospective candidate.
"I will assure my counterparts: The path towards the European Union remains open if you choose reforms and progress instead of divisions and stalemate," Gabriel said.