The words the Croatian President used seem inappropriate, a spokeswoman for the EC, Pia Ahrenkilde Hansen, said in Brussels on Wednesday.
In response to journalists' questions whether she holds that the words Napolitano used, such as "bloodthirsty fury" were also inappropriate, the spokeswoman said, "We have no comment".
The trading of barbs between Italy and Croatia was triggered off last Saturday by President Napolitano's speech on a commemoration of Italians who were killed in karst pits (known as foibe) or who were driven from their homes in the Croatian and Slovene parts of the Adriatic coast in the aftermath of the Second World War.
During the commemoration, the Italian head of state said that the murders of Italians were a result of the "Slavic plan for annexation" and also spoke about "bloodthirsty fury that assumed the sinister contours of ethnic cleansing".
Croatia's Mesic hit back saying that it was "impossible to overlook elements of open racism, historical revisionism and political revanchism" in Napolitano's speech.