Both Mr. Obama and his secretary of state, John Kerry, have mentioned Israel’s needs as one justification for an attack on Syria. But some in Washington have already raised the specter of retaliatory missiles raining on Tel Aviv, as they did during the Persian Gulf war, as a reason not to strike. Michael B. Oren, Israel’s current ambassador to the United States, rebuffed that argument Sunday, saying in an interview, “Nobody can allege or assume that because of us America should not act.” Beyond that, Mr. Oren said, “the general disposition is not to be involved in this vote.”

A spokesman for the American Israel Public Affairs Committee, the main pro-Israel lobby, said Sunday that the group “won’t have comment for now.” Another advocate for Israel in Washington said people were waiting to see the White House strategy for the vote and how the debate unfolded before deciding what to do. Part of the hesitation comes from Jerusalem’s ambivalence about what outcome it prefers in the Syrian civil war.

“The only thing that is clear is that Israel will take the heat either way,” a senior Israeli government official said, speaking on the condition of anonymity because of Mr. Netanyahu’s directive. “If we remain on the sidelines, it will be seen as defiant criticism of President Obama. And if we don’t, it will be seen as interference. There is nothing we can do to come out clean.”

While Israel and its advocates seemed paralyzed by Mr. Obama’s move, analysts here generally condemned the decision to wait for Congressional approval, saying it weakened American leadership in the Middle East and made it more likely that Mr. Netanyahu would order Israeli military action against Iran on his own. Several experts said it was a significant setback, after months in which Jerusalem and Washington had seemed more in accord on the Iran question.

“The punch line is that the more that Israel perceives the U.S. as hesitant, the more Israel will be pushed to deal alone with the Iranians, something that the U.S. really did not want,” said Michael Herzog, an Israel-based fellow of the Washington Institute for Near East Policy. “People ask, ‘If this is the case on a relatively simple thing like striking Syria, how will they act against Iran?’ It deepens the question marks.”

Ari Shavit, a columnist for the left-leaning daily newspaper Haaretz, said that Israel and others in the Middle East were being left with a “feeling of orphans,” wondering “if there is still a reliable parent in Washington who is really committed, who understands what’s going on and who is willing to act.”