President Biden’s national security adviser said on Monday that while the United States was committed to Israel’s defense, Prime Minister Benjamin Netanyahu’s government had still failed to provide the White House with a plan for moving nearly a million Gazans safely out of Rafah before any invasion of the city.

In a lengthy presentation to reporters, the adviser, Jake Sullivan, also said Israel had yet to “connect their military operations” to a political plan for the future governance of the Palestinian territory.

Mr. Sullivan, who has been at the center of the administration’s response to the Oct. 7 terrorist attack on Israel and its aftermath, described in detail the administration’s objectives in intervening to achieve a cease-fire and a return of hostages, including Americans, still in the hands of Hamas. But beneath repeated expressions of support for Israel, he made clear Mr. Biden’s frustration in dealings with Mr. Netanyahu, after a series of heated conversations between the two men.

Mr. Sullivan insisted that the only weapons Mr. Biden was withholding from the Israelis were 2,000-pound bombs, for fear that the U.S. munitions, which can level whole city blocks, would be employed by Israel in its effort to rout Hamas leaders from their tunnel network, deep under the city.

The United States, he noted, was still sending defensive weapons, and a range of offensive arms that did not run the risk of major civilian casualties.

“We still believe it would be a mistake to launch a major military operation into the heart of Rafah that would put huge numbers of civilians at risk without a clear strategic gain,” Mr. Sullivan said. “The president was clear that he would not supply certain offensive weapons for such an operation, were it to occur.”