An Israeli soldier in the Golan Heights, near the Syrian border, on Wednesday. Israelis were concerned what message Iran might take from a diplomatic push.

But there was also pessimism in Israel that the Syrian president, Bashar al-Assad, would actually fulfill his promise to turn over and ultimately destroy his chemical stockpile. Instead, many analysts worried that Mr. Assad, his Iranian patrons and the Lebanese militia Hezbollah would emerge strengthened, and that the main upshot of the episode would be a sense of American wavering on involvement in the Middle East.

“When the Iranians see this, they don’t fear a military threat,” Tzachi Hanegbi, an Israeli lawmaker with security expertise who is close to the prime minister, Benjamin Netanyahu, told Israel Radio. “To the contrary, they feel the international coalition is weak and stuttering and not enough of a reason to give up their nuclear program.”

Dan Gillerman, a former Israeli ambassador to the United Nations, said the message to Iran was that “America’s allies cannot rely on it, that its enemies can do what they want and nothing will happen to them.” Avigdor Lieberman, Israel’s former foreign minister and Mr. Netanyahu’s political partner, reacted to the developments with what has become practically a mantra here, “We rely only on ourselves.”

Mr. Netanyahu, breaking a week of silence on the Syria situation, echoed his colleagues by saying that Israel’s main concern was how it relates to what it sees as its greatest threat: the potential for Iran to build a nuclear bomb. And in his view, the message seemed to be that Israel needed to be prepared to take care of itself.

“The world needs to make sure that anyone who uses weapons of mass destruction will pay a heavy price for it,” Mr. Netanyahu said Wednesday at the graduation ceremony for a naval program. “The message in Syria will also be heard very well in Iran.”

He cited President Obama’s speech Tuesday, in which he said that Israel could defend itself but also had Washington’s “unshakable support,” and quoted a famous saying of the ancient Jewish scholar Hillel, “If I am not for myself, who will be for me?”

“The operational translation of this rule is that Israel should always be able to defend itself and will protect itself by its own strengths against every threat,” Mr. Netanyahu told the crowd. “The state of Israel is today prepared to act with great strength.”

Israel has insisted throughout Syria’s two-and-a-half-year-old civil war that it will not intervene except to protect its border or to prevent the transfer of weapons to Hezbollah. There is a stark divide here over whether Mr. Assad’s continued rule is preferable to a victory by Syrian rebel groups, some of whom are allied with Islamic extremists seen as even bigger threats. There is a growing sense that a continuation of the bloody battles may be the best outcome for now.

But Israelis have largely been disappointed by what they describe as Mr. Obama’s indecision — a sharp contrast from their own military secretly striking weapons convoysin Syria that it suspected were bound for Hezbollah several times this year.

Ehud Yaari, a fellow of the Washington Institute for Near East Policy who is based in Jerusalem, said Israelis were dubious about the diplomacy and “confused at the performance of the president.” There was also a concern that both Syria and Iran might obtain advanced Russian weapons systems as part of the deal after the Russian newspaperKommersant reported on Wednesday that Russia had agreed to give Iran advanced S-300 antiaircraft missiles and build an additional nuclear reactor at the Bushehr nuclear site.

“They got the distinctive feeling that the president was looking for every possible way to avoid acting on the red line which he himself issued,” said Mr. Yaari, a television analyst here with close ties to Israel’s security and intelligence establishment. If Mr. Obama’s “not willing to have a very modest, limited strike on Syria, a punitive strike,” he added, “when we come to that, would he be contemplating a bigger move on Iran?”

But Jonathan Spyer, a senior research fellow at the Interdisciplinary Center in Herzliya, said it was wrong to “draw a simplistic parallel” between Syria and Iran, which the United States has vowed to prevent from developing a nuclear bomb and which is seen as not only as a threat to Israel but a problem for the world.

“The place of Syria and the place of Iran among U.S. national security priorities are very different,” Mr. Spyer said. “If Iran is No. 1 on the list, and Syria is No. 25, you wouldn’t expect the same amount of attention to No. 25 as you would at No. 1.”

Still, Mr. Spyer said he expected that Mr. Assad would turn the Russian plan into an “epic, mammoth filibuster,” and that Israel would probably be left facing an antagonistic nation to the north still harboring chemical weapons as well as an Iran emboldened by a “sense that the West squirms about making statements and then tries not to fulfill them without looking stupid.”

One upside for Israel is that it will not be blamed in America, as many here worried in recent days, for another unpopular military engagement in the Middle East. And if some analysts view the diplomatic proposal as a sign of Washington’s weakness, others say it allows Mr. Obama to avoid what would be a far more humiliating defeat in Congress.

“As one person put it to me, this could be something that could work, and it could also be a way to save face for the administration,” said Matthew Levitt, the author of a new book on Hezbollah, who has been consulting with many senior Israeli security officials. “The question is, do we hold everybody’s feet to the fire and make sure something happens in the near term, and do we do things to rebuild credibility about our longstanding position, whether with Syria or Iran, that when we say things, we mean it.”