Biden’s statement comes as Israel presses ahead with its military operation in Rafah, a city in the south of Gaza.
Israel Defense Forces (IDF) troops have taken control of the Philadelphi Corridor, a strategically important thin strip of land which separates Gaza from Egypt.
It comes after dozens were killed in an Israeli air strike near Rafah on Sunday, which triggered a fire that engulfed tents where displaced people were sheltering.
The US and other allies of Israel had urged its government not to press ahead with the operation because of the high risk of civilian deaths.
Meanwhile, IDF troops have pulled out of Jabalia in northern Gaza, after a three-week offensive there which saw tens of thousands of civilians flee the area.