The official did not identify specific countries where Israelis might be targeted. But he said Israel has "general information reflecting intent," citing findings from investigations into the attacks overseas.
"Iran and Hezbollah are continuing to try to carry out other attacks on targets abroad," he said, without offering details. "That means asking Israelis abroad to be vigilant."
Earlier this week, assailants planted a bomb on an Israeli Embassy car in India, critically injuring a diplomat's wife, and attempted two botched bombing efforts against Israeli diplomats in Georgia and Thailand.
Israel has blamed Iran for all three incidents and there has been speculation that Hezbollah, the Lebanese militant group, carried them out on behalf of its Iranian patron. Iran and Hezbollah have denied involvement in all three attacks.
The attacks took place in countries that have cordial relations with Tehran. That Iran would risk diplomatic dust-ups with such countries was evidence of just how determined it is to attack Israeli targets, the counterterrorism official said.
The U.S. government is worried that Iran will consider a terror attack on American soil, but it has no specific or credible threat about such a plot. Police from Los Angeles to New York City said they were anxious about the risks, even as a senior U.S. intelligence official reassured Congress that it was unlikely Iran would attack.
Los Angeles, which has one of the largest Iranian communities outside Iran, has moved potential Iranian threats to the top of its intelligence briefings over the past few weeks.
The New York Police Department said it assumes Iran would attack the city, with its especially large Jewish population.
"The attacks overseas raises everybody's anxiety level a little bit," said Deputy Chief Michael Downing, commander of the Los Angeles Police Department's counterterrorism and special operations bureau.