Foreign Minister Silvan Shalom told Israel Radio on Saturday that he had just spent a week in the US trying to stop the "all out party" by Palestinians looking for reaction to the court ruling at the Security Council.
"I am therefore assuming ... that there is a good chance there will be a veto," he added.
Shalom added he was sure the court's decision "will go to the Security Council because they [Palestinians] can muster an automatic majority in the UN General Assembly."
But only the 15-nation Security Council can take action on the ruling. Israel is expecting its US ally to veto any resolution.
Tel Aviv has said the ruling is invalid because it fails to address its alleged reason for building the barrier on occupied Palestinian land - its own security.
However, three times as many Palestinians have been killed since the beginning of the al-Aqsa Intifada than Israelis.
Palestinians call the barrier an "apartheid wall" that will deny them a viable state and has separated thousands of people from their fields, schools and hospitals.
Officials said they would demand the Security Council take action.
"I am therefore assuming ... that there
is a good chance there will be a veto"
Israeli foreign minister commenting on UN vote
But US officials have already made clear they oppose UN involvement in resolving the issue.
"We do not believe that that's the appropriate forum to resolve what is a political issue," said White House spokesman Scott McClellan, adding it should be tackled through an internationally-backed road map to peace.
The World Court, the UN's highest tribunal, issued a non-binding ruling on Friday that the partially-built barrier erected on occupied Palestinian territory was unlawful.
It said Israel must tear down the barrier and pay compensation to those who had lost their homes and land.
"The wall ... cannot be justified by military exigencies or by the requirements of national security," its head, Judge Shi Jiuyong, said.
But Israel has already vowed to keep building the 600km barrier, which is about one-third complete.
Its route curves around illegal settlements deep inside the occupied West Bank. When contacted by Aljazeera.net, no Israeli official at the Ministry of the Interior would explain why Tel Aviv had not built the barrier on the Israeli side of the border.