But the activist actress explained the rationale behind not attending the fete, for which she was going to be the prize laureate -- it was a direct rebuke against Israeli Prime Minister Benjamin Netanyahu.
In a post on the Oscar winner's Instagram account she wrote: "I chose not to attend because I did not want to appear as endorsing Benjamin Netanyahu, who was to be giving a speech at the ceremony."
She added that she is not part of a Palestinian-inspired movement known as Boycott, Divestment, Sanctions, or BDS. Instead, she said she was determined to hold Israel's leadership accountable for what she stated were a mix of malfeasance.
"The mistreatment of those suffering from today’s atrocities is simply not in line with my Jewish values. Because I care about Israel, I must stand up against violence, corruption, inequality, and abuse of power," she wrote. "Like many Israelis and Jews around the world, I can be critical of the leadership in Israel without wanting to boycott the entire nation."
Portman stressed that she intends to support "a number of charities in Israel," which she said she will name soon.
But the organization that was set to recognize Portman, the Genesis Foundation, which launched in 2003 to laud Jewish achievement to the humanities, announced that it was "very saddened" by her decision.
The foundation still maintains Portman's picture and accolade on its website and has a banner that reads: "Congratulations Natalie Portman, 2018 Genesis Prize Laureate."
It announced it was canceling the prize ceremony, however, which was scheduled for June 28.
"We fear that Ms. Portman's decision will cause our philanthropic initiative to be politicized, something we have worked hard for the past five years to avoid," according to a statement.
Portman was criticized by some in the Israeli government. Energy Minister Yuval Steinitz stated that to boycotting Israel "has elements of anti-Semitism."
And the country's Internal Security Minister Gilad Erdan penned a letter to Portman alluding to “Star Wars” metaphors to drive home his point.
“Anakin Skywalker, a character you know well from Star Wars, underwent a similar process. He began to believe that the Jedi Knights were evil, and that the forces of the Dark Side were the protectors of democracy.
“I call upon you not to let the Dark Side win.”
Netanyahu had not responded to Portman's award snub as of Sunday afternoon.
Portman did not specify what Netanyahu had specifically done to cause her to boycott the award ceremony.
But the prime minister has drawn criticism for his handling of Palestinian affairs, among other foreign matters. He has also been suspected of corruption at home.
In February, Netanyahu was questioned for more than four hours by the Israeli police at his residence in Jerusalem as part of an investigation of a corruption case; he still remains a suspect in the case.
Israeli police announced at the time that there was "sufficient evidence" against the prime minister in both cases "for the offense of accepting bribes, fraud and breach of trust." Israeli police accuse Netanyahu, known by the nickname "Bibi", of accepting at least 1 million shekels, around $283,000, in gifts and bribes.