"There are no embassy travels [sic] to Gaza. This applies also for all US government travel. Exceptions could be made on a case-by-case basis," said Paul Patin, spokesman for the US embassy in Tel Aviv, on Friday.
Charles Hunter, spokesman for the US consulate in Jerusalem, said: "No trips by the consulate to the West Bank have taken place since the bombing. We are assessing the situation to know when visits can resume."
After Wednesday's bombing, which killed three Americans, the US called on its nationals in Gaza to leave the territory and urged those in the West Bank to take precautions against possible future attacks.
A senior US official said it was the first fatal attack that had deliberately targeted American nationals during a three-year-old Palestinian uprising against Israel for statehood.
"There is no question they were aiming for American government personnel," the US official said, adding "It is the twisted mind of terrorism. People in this situation don't want us there. They think we're biased."
"There has not been a credible claim of responsibility and we don't have a credible address for going after (anyone)"
Unnamed US official
The official said the embassy had ordered diplomats already in Gaza to leave, and that the US consulate in East Jerusalem had called on Americans visiting the West Bank to do the same.
No group has claimed responsibility for the attack.
Asked about the investigation, the senior US official said: "There has not been a credible claim of responsibility and we don't have a credible address for going after (anyone)."
The guards were killed in Gaza on Wednesday when a bomb, set off apparently by remote control, wrecked their armoured jeep. A team from the Federal Bureau of Investigation and Palestinian security officials are now investigating the attack.