US lawmakers were informed of the sale in early May, nearly a week before violence erupted between Israeli forces and Hamas militants, a senior congressional source confirmed to Al Arabiya English.
The Washington Post, which first reported the sale, quoted an unnamed Democratic lawmaker criticizing the move: "Allowing this proposed sale of smart bombs to go through without putting pressure on Israel to agree to a cease-fire will only enable further carnage."
Washington has found itself in a difficult position, with Biden attempting to make human rights a pillar of his foreign policy. But Israel, which must always have military superiority in the region according to US law, has so far succeeded in pushing the US to block UN Security Council statements on the violence.
Members of Biden's Democratic Party have been among the most vocal critics of Israel in recent weeks. The latest weapons sale quickly drew criticism from the Democratic Party, while Republican officials have demanded Biden help replenish Israel's so-called Iron Dome missiles.
The US lawmakers have reportedly questioned the new proposed sale, its timing and suggested it may be used as leverage, the Washington Post added.
According to the Palestinian health ministry, at least 200 Palestinians have already been killed in Israeli airstrikes on Gaza and over 1,000 injured.
Once Congress is officially notified of the sale, lawmakers will have 20 days to object to the deal with a nonbinding resolution of disapproval, according to the Washington Post.