Citing new violence between Israel and Gaza, the U.S. Embassy in Tel Aviv told staff members not to travel to the South and encouraged U.S. citizens "to exercise caution."
"Non-essential official travel by Embassy staff to the south of Israel remains prohibited," said the advisory sent Thursday, the second night of bombing exchanges between Israel and the Gaza Strip.
The statement also said the embassy would have low staff on Friday and that embassy families should keep their children home from school on that day.
One of the more than 250 rockets fired from Gaza since hostilities intensified on Wednesday hit close to Tel Aviv.
Israel has not shut down schools in the city, although it has ordered no school within 25 miles of the Gaza Strip.
Sixteen Palestinians, including two children and a top terrorist leader, and three Israelis have been killed in the exchanges. The three Israelis were in an apartment building hit by a rocket in the southern town of Kiryat Malachi.
"U.S. citizens are encouraged to exercise caution and take appropriate measures to ensure their safety and security in light of the escalating level of violence in Gaza and Israel," the embassy advisory said.
"U.S. citizens should pay close attention to their surroundings and news reports, and follow the civil defense guidance provided by the Home Front Command."