PRISTINA, Kosovo — The European Union official who oversees the process for admitting new member countries has urged Kosovo's government to rescind a recently imposed 100 percent tariff on goods from Serbia and Bosnia-Herzegovina.

EU Enlargement Commissioner Johannes Hahn met with Kosovo's top officials in Pristina after Monday morning talks with Serbian President Aleksandar Vucic in Belgrade. While still in Serbia, Hahn wrote on Twitter that he planned to call on Kosovo officials "to unblock regional cooperation and trade" and stressed the need for dialogue.

Last month, Kosovo's government imposed the tariff on Serbian imports saying it would stay in place until Serbia recognizes Kosovo's independence and stops preventing it from joining international organizations such as Interpol.

Hahn said the EU was "disappointed" about the introduction of tariffs on imports and considered it as "unacceptable" and against the principles of regional cooperation, which is the first step toward EU membership.

"It undermines all the good work done and has a negative impact on the whole region," he said at a news conference.

After meeting with Hahn, Kosovo Prime Minister Ramush Haradinaj said his government was "obliged to take this step following continuous obstacles that Serbia has done and continues to do to Kosovo.

Haradinaj added that the tax does not include humanitarian donations coming from Serbia and Bosnia.

Kosovo unilaterally declared independence from Serbia in 2008. The EU has said that normalized ties between the two are a condition for the countries to become members. But seven years of EU-mediated negotiations appear to have stalled amid revived friction between Pristina and Belgrade.

Serbia's leader said he was ready to return to the negotiations as soon as Kosovo lifts the sanctions on Serbian imports.

"Pristina's (tax) measures lead to the full destabilization of the whole region and could lead to the escalation of tensions," Vucic said in a statement.

Ten lawmakers representing Kosovo's ethnic Serb minority closed themselves inside their Parliament office Sunday to protest the import tariffs, asking for a meeting with Hahn to express their concerns. The head of the EU office in Pristina met with them Monday, but they remained in the office awaiting Hahn.

Also Monday, the speaker of Kosovo's parliament, Kadri Veseli, said the 120-member assembly would vote Dec. 14 on transforming the country's security forces into a regular army. Serbia has protested the move and threatened unspecified retaliatory measures.

Western countries, including the United States, and NATO have opposed having lawmakers decide the issue through votes on three proposed laws. They want it considered through constitutional amendments, which would need approval from ethnic Serb minority lawmakers to pass, too.