Samira Ibrahim -- who stood up for women's rights during the Tahrir Square protests in Egypt -- was one of 10 people named as recipients of the award, to be presented by first lady Michelle Obama and Secretary of State John Kerry at a ceremony.
The conservative U.S. publication The Weekly Standard published the questionable tweets -- including one in which she called the fatal bombing of six Israeli tourists in Bulgaria "very nice very nice news."
After U.S. State Department officials raised the issue with Ibrahim, she initially said her account was hacked, the Jewish Telegraphic Agency said Saturday.
Ibrahim subsequently said her refusal to repudiate the tweets prompted the State Department to withdraw the award.
"I refused to apologize to the Zionist lobby in America on the previous statements hostile to Zionism under pressure from the American government, so the prize was withdrawn," a posting on her Twitter account read.