The latest incident in the strategic Strait of Hormuz comes amid soaring tensions between the two countries, with Washington already reeling from Iran shooting down one of its drones last month.
US President Donald Trump claimed an American naval vessel downed an Iranian drone on Thursday that threatened the ship as it was entering the strait – a claim vehemently denied by Tehran.
Iran's armed forces dismissed Trump's assertion as "baseless and delusional" while admitting one of their drones was flying near the US ship.
"All of (Iran's) drones... have safely returned to their bases," said Armed Forces spokesman Brigadier General Abolfazl Shekarchi.
"There have been no reports of a confrontation with the American USS Boxer" naval vessel, he added, quoted by Tasnim News Agency.
The Revolutionary Guards said they will "soon" publish photos taken by one of their drones of the USS Boxer.
Images were transmitted to base "before and even after the time Americans claim" the drone was destroyed, according to a statement on the force's Sepahnews website.
The Pentagon claimed the ship "was in international waters" when a drone approached at approximately 10:00 am local time (0530 GMT).
But Iran's Deputy Foreign Minister Abbas Araqchi quipped that the US may have actually downed one of its own aircraft.
"I am worried that USS Boxer has shot down their own (drone) by mistake!" Abbas Araqchi tweeted on Friday.
The confrontation comes after Tehran in June shot down an American surveillance drone flying over its airspace and a series of attacks on oil tankers in the Persian Gulf and Gulf of Oman.
Washington claimed that Tehran was behind the attacks, however Iran rejected the US accusations.
UK extends detention of Grace 1
The tanker troubles further intensified on July 4, when Gibraltar detained a vessel carrying Iranian oil. Gibraltar's Supreme Court ruled on Friday that the Grace 1 supertanker can be detained for 30 more days.
US officials claimed the vessel was destined for Syria to deliver oil, in violation of separate sets of European Union and US sanctions.
Following the seizure Iran branded the move "piracy" and has called for immediate release of the tanker.
The incidents have raised fears of a regional conflict involving the US and its allies in the Persian Gulf region, through which nearly a third of the world's oil is transported.
Iran not seeking war
The top commander of Iran's Islamic Revolution Guards Corps (IRGC) said they were not seeking to "initiate a war" but would respond to hostilities.
"If enemies make a mistake in calculation, our defensive strategy and all our capacities will change to offensive," said General Hossein Salami, quoted by Sepahnews.
His comments came after the IRGC said Thursday they had seized a "foreign tanker" believed to be the Panamanian-flagged vessel Riah and its crew for smuggling Iranian fuel.
Smuggling Iran’s fuel
The IRGC released details of its recent capturing of the foreign tanker smuggling one million liters of Iranian fuel near the Strait of Hormuz.
A local IRGC naval command post published the details in a statement, which was carried by Tasnim News Agency on Thursday.
According to the statement, the incident took place to the south of the Iranian Larak Island on Sunday.
IRGC naval forces, which were patrolling the waters on an anti-smuggling mission, acted against the vessel in a “surprise” operation upon ascertaining the nature of its cargo and securing the required legal approval from Iranian authorities.
The ship had loaded the fuel from Iranian dhows and was about to hand it over to other foreign vessels in farther waters. The vessel, which had 12 foreign crewmembers aboard at the time of the seizure, is capable of carrying two million liters of fuel.
"The [Iranian] naval units in this area will continue to conduct security operations and missions aimed at confronting organized fuel smuggling efforts ... decisively and keenly around the clock,” the statement added.
The forces “do not hesitate for a moment to preserve the Iranian nation’s interests and assets,” it noted.
The statement also rejected reports by some Western media outlets trying to accuse the IRGC of seizing another vessel in recent days.
AFP and Press TV contributed to this story.