"We decided that we needed to take a closer and harder look at them in light of the additional information we received," said Gallegos.
He also said the visas were canceled under a prudential revocation clause in immigration rules that allows them to be rescinded based on information gleaned about the holders after they were issued.
"It does not preclude the applicants from reapplying for visas in the future," he said.
Gallegos declined to comment on the nature of the new information about the four Palestinians, one of whom had actually arrived at Dulles International Airport outside Washington before he was told his visa had been revoked and was forced to return to Jordan.
But another official familiar with the situation said the information related to security issues that were behind the refusal by Israeli authorities to allow them to leave Gaza to be interviewed for visas at the U.S. Consulate in Jerusalem in May.
The official spoke on condition of anonymity due to privacy concerns about visa records.
The visa revocations were first reported by The New York Times.
Palestinian students cannot apply for U.S. visas in Gaza because Washington does not recognize the territory's Hamas government and has no diplomatic presence there. Israel bans all Gaza students from leaving for security reasons but has made exceptions on a case-by-case basis.
Rice had been infuriated when State Department officials canceled the Fulbright scholarships of seven Palestinian students whom Israel had refused to let leave Gaza for their visa interviews.
After she took their cases to senior Israeli officials, Israel allowed four of the seven to travel to Jerusalem for interviews in June. Although Israel opposed the move, U.S. diplomats then made a rare trip to the Gaza border in July to interview the remaining three.
One official said Rice, who had been outspoken about the negative signal the original cancellations sent to Palestinians and the broader Arab world, had ordered a top-to-bottom review of the entire Fulbright scholarship vetting process in the wake of the cancellations.