Macedonian President Gjorge Ivanov said police prevented what he calls a "coordinated terror attack" after an armed group battled officers in northern Macedonia Saturday.
The fighting in the city of Kumanovo left 22 people dead, including eight police officers and 14 gunmen. Thirty-seven policemen were wounded.
President Ivanov told a meeting of the Macedonian national security council Sunday that the gunmen were trying to cause chaos and fear, and that the lives of civilians were at risk.
"The perpetrators of this terrorist act and all those involved will pay dearly for what they tried to do to the Republic of Macedonia and its citizens. I want to clearly point out that we will not allow escalation of tensions."
Kumanovo is in an ethnic-Albanian area north of the capital, Skopje.
It is unclear who the gunmen were. Ivanov described them as extremely violent and skilled criminals with military training. A police spokesman tells the French News Agency they were mostly Macedonian citizens led by five ethnic-Albanians from Kosovo.
President Ivanov said Macedonia warned 17 European Union and NATO members about the group and the risk it posed earlier this year, but got no response.
EU and NATO officials did not comment on Ivanov's assertion Sunday, but did call for calm.
Macedonia's ethnic Albanians launched a 2001 insurgency for more civil rights and autonomy. A Western mediated peace deal made Albanian an official language in Macedonia and also gave ethnic Albanians a greater role in government and the military.