We know what that led to in the Balkans in the past. We can't just stand by and watch, Lajcak said after a meeting of the Visegrad Group.
He expects the European Union to adopt soon a position on Berisha's statements about uniting Albanians in the countries in which they live in the Balkans.
He said the foreign ministers of the Visegrad Group, Baltic and Scandinavian countries had expressed concern over the statements at a meeting in Gdansk on Wednesday.
According to US media, the United States has recently warned NATO ally Albania to stop fomenting nationalism before elections so as not to destabilise the region. Faced with expectations of a tight race at parliamentary elections in June, Berisha is disturbing Albania's neighbours, in which millions of ethnic Albanians live, with his nationalist statements.
In a letter to the Albanian Foreign Ministry last Friday, the State Department said Albanian leaders were entering potentially dangerous territory given the history of ethnic conflicts in the Balkans. It added that such statements could incite violence, threaten peace and security, and impact US-Albanian relations.
The State Department also urged Albanian politicians to keep out of Serbia's affairs. Serbia is conducting delicate negotiations with Kosovo under the EU's auspices aimed at normalising relations.