Western allies call for more time for sanctions to work, as tensions run high following Iranian naval deployment.
The United States and Britain have urged Israel against any military action against Iran and its nuclear programme, after Iranian warships passed through the Suez Canal to dock at the Syrian port of Tartous, ratchetting up tensions in the region.
Martin Dempsey, the chairman of the US joints chiefs of staff committee, and William Hague, the British foreign minister, both said that an Israeli attack on Iran would destablise the entire region, and urged Israel to give international sanctions against Tehran more time to work.
In comments on Sunday, Dempsey said an Israeli attack would be "not prudent", and Hague said it would not be "a wise thing".
In an interview broadcast on CNN on Sunday, Dempsey said Israel has the capability to strike Iran and delay the Iranians "probably for a couple of years. But some of the targets are probably beyond their reach".
He expressed concern that an Israeli attack could spark reprisals against US targets in the Gulf or Afghanistan, where American forces are based. "That's the question with which we all wrestle. And the reason that we think that it's not prudent at this point to decide to attack Iran,'' Dempsey said.
Describing Iran as a "rational actor", Dempsey said he believed that the international sanctions on Iran are beginning to have an effect. "For that reason, I think, that we think the current path we're on is the most prudent path at this point."
Tom Donilon, the White House national security advisor, was to meet with Binyamin Netanyahu, the Israeli prime minister, though there was no confirmation from either government on whether or not that meeting took place.
Donilon is due to meet Ehud Barak, the Israeli defence minister, on Monday.
Al Jazeera's John Terrett, reporting from Washington DC, said it was highly unusual for a national security advisor to travel overseas and that he was likely to bluntly tell the Israelis to "put the brakes" on its attack plans.
Speaking to the BBC, British Foreign Minister Hague said the UK's approach was focused on sanctions and diplomatic means.
"I don't think a wise thing at this moment is for Israel to launch a military attack on Iran," he said. "I think Israel like everyone else in the world should be giving a real chance to the approach we have adopted on very serious economic sanctions and economic pressure and the readiness to negotiate with Iran."
Warships enter Mediterranean
Iranian warships crossed the Suez Canal and docked in Syria's port of Tartous on Sunday, Iranian state media reported.
The Mehr news agency said on Sunday that Tehran's show of support has caused "extreme worry for Zionist forces".
Youcef Bouandel, professor of international affairs at Qatar University, told Al Jazeera that Iran's deployment has to be viewed as part of a "broader picture", because the Iranian government feels that "Syria is the first step towards putting Iran in the corner".
"Iran has been having a few standoffs with the West in general over its nuclear programme and over its oil embargo," said Bouandel, who added that the docking of the ships on the Syrian coast had two largely symbolic meanings.
"Iran has been threatening to close the Strait of Hormuz and has been a strong ally of Syria over the last year in particular ... The two ships ... crossed the Suez Canal without being stopped or searched [which] suggests that they do not carry any weapons," he said.
Tensions over the nature of Iran's nuclear programme have led to ever-tightening sanctions on the country's oil exports, prompting Iran to threaten to close the strait, the world's most important chokepoint for oil transport.
Reacting to the news on Saturday, Israel's foreign ministry denounced the deployment as a "provocation" and a "power play". Israel said it will be watching the ships' movements closely to ensure they do not approach its coast.
There have been increasingly frequent media reports, as has been the case in the past, citing Israeli officials who say they must bomb Iran's nuclear facilities before the government acquires the ability to construct a nuclear bomb.
Israel has expressed some satisfaction with recent harsh sanctions passed against Iran's financial sector but does not believe they alone will lead Tehran to re-evaluate its nuclear program, said Shamayleh, reporting from Jerusalem.
Israeli officials accused Tehran of orchestrating anti-Israeli bombings in India and Georgia as well as blasts in Thailand last week, allegations that Iran denies.
Iran has accused Israel of assassinating several of its nuclear scientists.
Iran carries 'message of peace'
In remarks carried by the official IRNA news agency, Iranian Admiral Habibollah Sayari did not say how many vessels had crossed the canal or what missions they were planning to carry out in the Mediterranean, but he said the flotilla had previously docked in the Saudi port city of Jeddah.
Two Iranian ships, the destroyer Shahid Qandi and supply vessel Kharg, had docked in the Red Sea port on February 4, according to Iranian media.
Sayari said the naval deployment to the Mediterranean would carry a "message of peace" but also put on display "the might" of Iran's military.
"It will prove to the world that despite increasing enemy sanctions over the past 33 years, our manpower, obedient to the orders of the leader Imam Khamenei, continue to add to their academic and military abilities," Sayari said.
The first Iranian presence in the Mediterranean in February 2011 provoked strong reactions from Israel and the US.
During the 2011 deployment, two Iranian vessels, a destroyer and a supply ship, sailed past the coast of Israel and docked at the port of Latakia in Syria before returning to Iran via the Red Sea.
Russia, who has close relations with Iran and has at every turn opposed military action against Syria, also has a base in Tartous.