Israel is preparing for an Iranian attack in the next two days, and the U.S. is restricting travel by its diplomatic personnel in Israel, The Wall Street Journal reported Friday.

The attack on southern or northern Israel is expected as early as Friday or Saturday, a source familiar with the situation told the newspaper. A person briefed by the Iranian leadership, however, told the Journal that though such plans are being discussed in Tehran, a final decision has not yet been made. 

The U.S. embassy, meanwhile, said staff had been told not to travel outside the greater Jerusalem, Tel Aviv or Beersheba areas "out of an abundance of caution," the BBC reported.

President Biden noted on Wednesday that Iran was threatening to launch a "significant attack," and he vowed to offer "ironclad" support to Israel. 

Iran, which is backing Hamas fighters in the Israeli conflict, has vowed to retaliate against Israel, blaming the country for a strike on its consulate in Syria 11 days ago, killing 13 people, though Israel has not claimed responsibility for the attack. 

Israeli Prime Minister Benjamin Netanyahu said his government was ready to meet any challenge, and warned that Israel would harm any country that caused it harm.

This is a developing story. Please check back for updates.