No decision had been made to send troops into Iran itself, two of the officials told Reuters, but they will build up the capacity for potential future operations in the region.
The deployments of the USS Boxer, an amphibious assault ship, along with its Marine Expeditionary Unit and accompanying warships, come after Reuters reported that US President Donald Trump's administration was considering deploying thousands of troops to reinforce its operation in the Middle East.
Trump told reporters on Thursday that he was not putting troops "anywhere" but that if he were to do so, he would not tell journalists.
The sources, who spoke on condition of anonymity to discuss future deployments, did not say what the role of the additional troops would be.
One of the officials said the troops were departing the west coast of the United States about three weeks ahead of schedule.
The expeditionary unit has about 2500 Marines.
The additional deployments will add to the 50,000 US troops already in the Middle East and would bring two Marine Expeditionary Units to the region.
The US has carried out strikes against 7000 targets inside Iran and hit more than 40 Iranian mine-laying vessels and 11 submarines, the Pentagon says.
As Muslims around the region tried to celebrate Eid al-Fitr, which ends the fasting month of Ramadan, and Iranians marked Nowruz, the Persian New Year, the prospect of a quick end to a war seemed remote.
A speech attributed to Mujtaba Khamenei, Iran's new supreme leader who has not been seen in public since an Israeli attack that killed his father and predecessor on the war's first day, was read out on state television on Friday for Nowruz.
Khamenei thanked the president, the government, the armed forces and the Iranian people for their resistance against the joint US-Israeli attacks.
The adversaries were not relying solely on military means such as missiles, drones and torpedoes, he said, adding that Iran's "front line" was broader than its enemies wished to acknowledge.
Khamenei declared the new Persian year the "year of the resistance economy in the spirit of national unity and security".
The supreme leader's message also urged all media outlets to exercise restraint and avoid highlighting vulnerabilities, warning that doing otherwise could help the enemy achieve its objectives.
He also denied that Iranian forces had carried out attacks on Turkey and Oman.
"The enemy believed that by targeting the leader (Ayatollah Ali Khamenei) and influential figures, it could instil fear and force the people to withdraw," Khamenei said in a Nowruz message on his Telegram channel.
"But the nation responded with unity ... resistance, and dealt a disorienting blow to the enemy."
In other developments, Iran attacked an oil refinery in Kuwait on Friday and Israel killed a spokesman of Iran's Revolutionary Guards.
Israel promised to avoid further attacks on Iran's South Pars gasfield the day after an Iranian retaliatory strike on Qatar caused damage that will leave the world short of natural gas for years to come.
Israel's military said it had attacked government facilities in Tehran.
Iranian state TV said Ali Mohammad Naini, deputy head of public relations for the Islamic Revolutionary Guard Corps was the latest of dozens of leading government and military officials to be assassinated by Israel.
In Tel Aviv and Jerusalem, air raid sirens howled as explosions from interceptors rang out.
The military said Iran had fired a barrage of missiles, and the ambulance service said at least one appeared to have carried dispersing cluster bombs.
with DPA and AP
