Is there an issue with Kohanim saying Birchas Kohanim when a non-Jew is present?
In שו"ת יוסף אומץ להחיד"א סי' ע' ס"ד he discusses this concept.
It seems that some had this custom - to not say Birchas Kohanim when a non-Jew was present.
It seems to be based on a misconception, and he rules that there is no issue with it.
In Shulchan Aruch, Orach Chaim (25:20) the Halacha states:
כ יִהְיוּ עֲשָׂרָה בְּמָקוֹם אֶחָד וְאוֹמְרִים קַדִּישׁ וּקְדֻשָּׁה, אֲפִלּוּ מִי שֶׁאֵינוֹ עִמָּהֶם יָכוֹל לַעֲנוֹת, וְיֵשׁ אוֹמְרִים שֶׁצָּרִיךְ שֶׁלֹּא יְהֵא מַפְסִיק טִנּוּף אוֹ עַכּוּ''ם.
A minyan is defined when the 10 are in the same room. Even people in other locations can answer Kadish and Kedusha. Some say that this only applies if nothing disgusting - nor עַכּוּ''ם - is between the Minyan and those in the other location.
Seems like some people took this to mean that if there's a non-Jew between them and the Cohanim, it would invalidate their ability to answer Amen, so they didn't do Birkat Cohanim if he was in the room.
However, the Halacha stated refers to another location - not the same room.
Besides, the Be'er Heitav (ibid) states that עַכּוּ''ם refers to an Avoda Zara, not a non-Jew.
עכו''ם. ר''ל שלא יהא עבודת אלילים מפסקת אבל עובד עבודת אלילים אינו מפסיק. מגן אברהם וכך כתב דבר שמואל סי' קפ''ט:
Sources / Hat tip: