A UK lecturers' union has urged its members to consider boycotting Israeli academics and universities.
The Israeli embassy says Natfhe will isolate its members with a boycott
Natfhe's annual conference backed a motion criticising what it called "apartheid policies" in Israel.
The 69,000 members were invited to consider a boycott of academics and universities which do not distance themselves from government policy.
But the UK's Israeli ambassador said the vote was seen around the world as an act of "blatant discrimination".
The motion, passed at Natfhe's conference in Blackpool, criticises what it calls the "exclusion wall" between Israel and parts of the Palestinian territories.
It also condemns "discriminatory educational practices" in Israeli higher education.
Tom Hickey, a philosophy lecturer from Brighton University who proposed the motion, said: "We are not telling people what to do.
"We want to make people aware that there is international concern over the situation."
Natfhe's general secretary, Paul Mackney, had urged delegates to vote against the motion.
It will remain policy until Natfhe merges with the Association of University Teachers (AUT) on Thursday, when it will be reduced to "advisory" status.
The Israeli Ambassador to the UK, Zvi Heifetz, said: "Israeli universities are open institutions, where students and teachers are selected on merit, regardless of their religious or ethnic backgrounds.
"As a means of promoting dialogue and coexistence in the Middle East, an academic boycott of Israel is counter-productive in the extreme.
"By pursuing such a policy Natfhe will isolate its members and their students rather than isolating Israeli academics, who are the forefront of international cooperation on academic study and research, including with Palestinian universities and institutions elsewhere in the Arab world."
He said there was widespread British and international support for Israeli universities against the Natfhe motion.
UK Foreign Office Minister Lord Triesman said the government believed academic boycotts were "conterproductive.
He said: "Far more can be obtained through dialogue and academic cooperation."
Last year, the AUT's annual council voted to sever all links with two Israeli universities, but this was later overturned.