Unfortunately the word "Nationalist" has developed connotation of being linked to "racism".
What you describe is a Nationalist/Patriotic act, Greeks were a part of the Ottoman State, the nation, so were all the other peoples living under the Ottoman nation.
Supporting only one ethnicity in a nation/state is RACISM, as you don't care about the whole country, just about a select part of it you feel is superior to the others.
The two are completely different.
Patriotism is just another word for Nationalism, Nationalism like all things in its extreme form is destructive, also when Racism is mixed into Nationalism it gets filthy.
However, loving your country, all the people in your country, your culture, being at ease with your identity and wanting to benefit your country is not a bad trait at all.