Iranian state media said a ballistic missile with improved capabilities demonstrated a new doctrine - Tehran "will take action against any threat even before it is carried out", the AP reported.
The report by Iran's state news agency repeatedly cited comments broadcast on state television the previous day by the head of Iran's Supreme National Security Council, Mohsen Rezaei.
He welcomed the new missile capabilities and claimed they had been "tested" against a US warship. It is unclear whether the missile tested was actually the missile.
On Saturday, the United States said ballistic missiles had been fired at American warships and had responded by hitting three Iranian oil tankers.
Experts called it a dangerous escalation, noting that Iran's previous attacks at sea had targeted merchant ships during a six-month war. The United States said the warships had avoided the attacks.
Iran's messaging has become more assertive in recent days, with a report on Monday saying the "Qassem Basir" marks a "turning point in Iran's defense strategy." It describes the missile as having greater range and accuracy and a half-ton warhead.
The missile was unveiled last year with a range of at least 1,200 kilometers.
Concerns about the ballistic missile program were one of the reasons cited by the United States and Israel for attacking Iran earlier this year, which sparked the war.