Lighting flares over Gaza
Lighting flares over GazaReuters

The United States on Monday warned Americans against traveling to Israel and Gaza, urging them to postpone any visits amid the current conflict.

It has also toughened restrictions on U.S. government staff and their families working in the country, including declaring the Old City in Jerusalem off-limits after dark until further notice, AFP reported.

"The U.S. Department of State warns US citizens of the risks of traveling to Israel, the West Bank and Gaza due to ongoing hostilities," an updated travel warning said, adding it "recommends that U.S. citizens consider the deferral of non-essential travel to Israel."

"The security environment remains complex in Israel, the West Bank, and Gaza, and US citizens need to be aware of the risks of travel to these areas because of the current conflict between Hamas and Israel," the State Department warning added, according to AFP.

The State Department highlighted that long-range rockets launched from Gaza have reached many parts of Israel, including Jerusalem and Tel Aviv.

While many have been intercepted by the Iron Dome shield, some have "caused damage and injury," the warning said, adding all American visitors should locate the nearest bomb shelter for their safety in case of more rocket fire.

"Travelers should avoid areas of Israel in the vicinity of the Gaza Strip due to the real risks presented by small arms fire, anti-tank weapons, rockets, and mortars, as attacks from Gaza can come with little or no warning," the statement added.

It stressed that while the embassy in Tel Aviv is working on reduced staffing and providing only emergency consular services, "we are not evacuating U.S. citizens out of Israel."

Earlier on Monday, the White House called on Israel to "do more" to protect civilians caught up in the crossfire of its assault on Hamas in Gaza.

"We would like the Israelis to take even greater steps to ensure the protection of civilians," spokesman Josh Earnest told reporters. His comments came as Secretary of State John Kerry headed to the region to push for a ceasefire.

Reaffirming Israel's right to defend itself, Earnest said it was "unacceptable" for Hamas "to continue firing rockets squarely at Israeli civilians."

On Sunday, President Barack Obama called for an "immediate ceasefire" in Gaza, as he spoke by telephone with Prime Minister Binyamin Netanyahu to express his concern after more than 100 Palestinian Arabs and 13 Israeli soldiers were killed in one day.

Obama, who also condemned attacks by Hamas on Israel, "raised serious concern about the growing number of casualties, including increasing Palestinian civilian deaths in Gaza and the loss of Israeli soldiers," the White House said in a statement quoted.

During their second call in three days about the escalating situation in Gaza, Obama and Netanyahu "discussed Israel's ongoing military operation," including "the loss of Israeli soldiers," the White House added.

It said Obama "reaffirmed Israel's right to defend itself."