The European Union's foreign-policy chief, Federica Mogherini, has urged Kosovo to rescind a 100 percent tax on imports from Serbia and Bosnia-Herzegovina, saying the measure "only complicates the situation further."
Federica Mogherini told Kosovar President Hashim Thaci during a phone call on November 28 that the levy "does not bring any solution to people's problems or to Kosovo's aspirations for its present and its future."
"This is a measure that does not help to build good neighborly relations and needs to be revoked," Mogherini also said, according to a statement.
On November 21, Pristina slapped the tax in retaliation for what it said were Belgrade's efforts to undermine the young republic on the international stage.
The move drew angry reactions from Belgrade and Sarajevo and calls from the European Union and the United States to revoke the measure. It also prompted the mayors of four predominantly ethnic Serb municipalities in northern Kosovo to resign.
The German government on November 28 called on the governments of both Serbia and Kosovo to "avoid escalation" of the ongoing standoff.
Spokesman Steffen Seibert criticized both Serbia's campaign to keep Kosovo out of Interpol, the international police organization, and Kosovo's subsequent decision to impose the 100 percent tariffs.
Relations between Pristina and Belgrade have been tense since Kosovo declared independence from Serbia in 2008.
Although more than 110 countries recognize Kosovo, Serbia -- and Bosnia -- do not.
Both Kosovo and Serbia have been told they must resolve their differences in order to make progress toward EU membership, but EU-sponsored normalization talks have been stop-and-go in recent months.
"We agreed the time is now for Kosovo and Serbia to reach an agreement" between Pristina and Belgrade, U.S. national-security adviser John Bolton tweeted after meeting with Thaci at the White House on November 27.
The meeting came a day after the Kosovar president held talks with U.S. Secretary of State Mike Pompeo in Washington.
During the talks, Pompeo urged Kosovo to rescind the tariffs on Serbian products and to work with Belgrade to "avoid provocations and deescalate tensions," the State Department said in a statement.
"Normalizing relations between Kosovo and Serbia is the only way to clear the path to both countries' future integration into the Western community of nations," it also said.