An editor-in-chief was attacked and beaten up after screening a documentary on her late husband, an ethnic Croat who helped Muslims during the Bosnian war.
The European Union condemned the attack and released a press statement stating, "in addition to freedom of the media, tolerance and respect between communities constitute core EU values that are highly relevant to countries with an EU membership perspective."
Stefica Galic, editor-in chief of tacno.net in Ljubuski, was attacked by a group of men and women in the Croat-dominated southern town while taking an evening stroll, local media reported. She required medical assistance but was not hospitalised.
Galic and her children had already been threatened and insulted by Croat nationalists before and after the screening, local media said.
The European Union called on the Bosnian authorities to "thoroughly investigate this incident and bring the perpetrators to justice."
During most of Bosnia's 1992-1995 war Muslims and Croats were allies against ethnic Serbs. However, they also fought against each other for 11 months in 1993 and 1994.
Sarajevo, which is lagging behind its Balkan neighbours in its bid to join the EU, wants to apply for membership status in the 27-nation bloc this year.