"I made it clear that if they go into Rafah ... I'm not supplying the weapons that have been used historically to deal with Rafah, to deal with the cities - that deal with that problem," Biden said on Wednesday in an interview with CNN.
Biden acknowledged US weapons have been used by Israel to kill civilians in Gaza, where Israel has mounted a seven-month-old offensive aimed at annihilating Hamas. Israel's campaign has so far killed 34,789 Palestinians, mostly civilians, the Gaza Health Ministry said.
Israel this week attacked Rafah, where more than one million Palestinians have sought refuge, but described it as a limited operation.
A senior US official, speaking on condition of anonymity, said Washington had carefully reviewed the delivery of weapons that might be used in Rafah and as a result paused a shipment consisting of 1800 2000-pound (900kg) bombs and 1700 500-pound (225kg) bombs.
US Defense Secretary Lloyd Austin said the decision was taken out of concern for Rafah, where Washington opposes a major Israeli invasion without civilian safeguards.
"Civilians have been killed in Gaza as a consequence of those bombs and other ways in which they go after population centres," he said when asked about 2000-pound bombs sent to Israel.
Israel's campaign in Gaza was triggered by Hamas' October 7 attack on Israel. That killed about 1200 people with about 250 others abducted, of whom 133 are believed to remain in captivity in Gaza, according to Israeli tallies.
Biden said the US would continue to provide defensive weapons to Israel, including for its Iron Dome air defence system.
"We're going to continue to make sure Israel is secure in terms of Iron Dome and their ability to respond to attacks that came out of the Middle East recently," he said.
"But it's, it's just wrong. We're not going to - we're not going to supply the weapons and artillery shells."
