Leaders of Kosovo and Serbia have failed to find a solution at a crisis meeting held in Brussels to ease heightened tensions between the two Western Balkan nations.
"Today there is not an agreement, but we don't give up," dpa news agency quoted Josep Borrell, EU foreign policy chief, as saying on Thursday in a statement.
Tensions have escalated between Serbia and Kosovo, with ethnic Serbs in northern Kosovo blocking roads and erecting barricades on July 31 to protest Kosovo's decision to oblige them to use vehicle license plates issued in Pristina.
The situation calmed after Kosovo agreed to continue to recognise Serbian-issued licence plates and documents for Kosovar citizens for another 30 days, until the end of August.
In his statement, Borrell said that there was still some time left to find a long-term solution to the dispute amid fears that leaving the issue unresolved could again lead to violence.
He added that Serbian President Aleksandar Vucic and Kosovar Prime Minister Albin Kurti will resume discussions "in the coming days".
"I think that both President Vucic and Prime Minister Kurti understood that there is not an alternative to the dialogue in order to solve this problem," Borrell said.
The top EU diplomat called the recent violence a "symptom" for the unresolved regional conflict.
Kosovo broke away from Serbia in 1999 following a war and declared independence unilaterally in 2008.
The EU has been trying to mediate between the two countries for years.
Expectations were low before the talks.
Vucic said on Twitter before the meeting that he was "hopeful for some kind of solution" but remained sceptical.