Israelis have long seen Europe as more hostile — even anti-Semitic in some pockets — but a slap from the United States has a particular sting.

“Rather than standing up for academic freedom and human rights by boycotting countries where professors are imprisoned for their views, the A.S.A. chooses as its first ever boycott to boycott Israel, the sole democracy in the Middle East, in which academics are free to say what they want, write what they want and research what they want,” Ron Dermer, Israel’s ambassador to the United States, said Monday.

America is viewed not only as Israel’s staunchest ally, but its best friend, and many analysts have fretted publicly in recent weeks that Prime Minister Benjamin Netanyahu’s outspoken opposition to the interim Iran nuclear deal had damaged relations with Washington.

Next month, the Modern Language Association’s annual meeting will debate a resolution calling on the State Department to criticize Israel for barring American professors from going to Gaza and the West Bank when invited by Palestinian universities.