The US has denied entry to a prominent Palestinian activist who co-founded the BDS movement.
Omar Barghouti was not allowed to board a plane Wednesday for a speaking tour that was to include Harvard University, New York University and a left-leaning synagogue in Chicago.
"Israel is not merely continuing its decades-old system of military occupation, apartheid and ethnic cleansing," Mr Barghouti said in a statement.
"It is increasingly outsourcing its outrageous, McCarthyite repression to the US and to xenophobic, far-right cohorts across the world," he said.
Mr Barghouti added he had also planned during the trip to attend his US-based daughter's wedding, saying: "I am hurt, but I am not deterred."
The Arab American Institute said that Mr Barghouti had a US visa valid until January 2021 but was informed by airline staff at Tel Aviv's Ben Gurion airport that US authorities had issued instructions denying him the right to travel.
State Department spokesman Robert Palladino said the United States does not explain individual visa decisions.
But without explaining why Mr Barghouti was rejected, Palladino said: "US law does not authorise the refusal of visas based solely on political statements or views if those statements or views would be legal in the United States."
The so-called BDS movement has infuriated Israel by calling for economic, cultural and academic boycotts of the Jewish state, including not buying products from Jewish settlements in the West Bank, as a way to press Israel to address the plight of Palestinians under occupation.
Elan Carr, the new US envoy to combat anti-Semitism, also said he could not discuss Mr Barghouti's case but branded the BDS movement anti-Semitic.
"An individual has a right to buy or not buy what they please. However, if there is an organised movement to economically strangle the state of Israel, that is anti-Semitic," he told reporters.
President Donald Trump has strongly backed Israel's Prime Minister Benjamin Netanyahu and has accused his Democratic rivals of anti-Semitism for distancing themselves from the right-wing leader.
Republican lawmakers in US states have increasingly pushed measures that would in turn refuse any government business with companies that participate in a boycott of Israel.