Iranian warships have crossed the Suez Canal and docked in Syria's port of Tartous, Iranian state media has 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 emabrgo," 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.
Put 'brakes' on Israeli attack
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.
Tom Donilon, the US national security advisor, was due to meet Binyamin Netanyahu, the Israeli prime minister, in Jerusalam on Sunday, and he was likely to warn against such a strike.
There have been reports, said Al Jazeera's Nisreen el-Shamayleh, that Donilon has "made it clear that the US does not support any kind of military action against Iran".
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.
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.
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.
The latest announcement comes amid heightened tensions between Iran and Israel, fuelled by a longstanding dispute over Tehran's nuclear programme and rising speculation that Israel might launch pre-emptive strikes against Iranian facilities.
William Hague, the British foreign minister, on Saturday warned that an attack on Iran would carry huge costs.
Although Iran's suspected drive for atomic weapons could lead to a dangerous nuclear standoff in the Middle East, he said he favoured more time to allow for increased diplomacy and economic pressure.
"We are very clear to all concerned that we are not advocating military action,'' Hague said.
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.