Several thousand people, mainly ethnic Albanians, protested in Macedonia's capital of Skopje and other cities on Friday to demand a fair trial for five people suspected in the slayings of five fishermen.
The fatal shootings have raised tensions because the suspects, who are all Muslims, were identified by the government as radical Islamists.
Protesters in Skopje chanted "Muslims are not terrorists!" Several stone-throwing youths smashed windows in government offices and court buildings, but no arrests were reported.
Police said six policemen, one reporter and one cameraman were lightly injured.
The five suspects have been charged with terrorism-related offenses over last month's killings. Two of the suspects remain at large.
Hundreds of people also joined protests in the cities of Tetovo, Kumanovo and Gostivar.
Macedonia has a dominantly Orthodox Christian majority, and a mainly Muslim ethnic Albanian minority, which makes up about a quarter of the 2.1-million population.