The Iranian Foreign Ministry has condemned the latest US strikes as a serious violation of the ceasefire and threatened retaliation.
"Undoubtedly, the Islamic Republic of Iran will not leave any act of mischief unanswered and will not allow even the slightest hesitation in defending Iran's national sovereignty," the ministry said in a statement on Tuesday.
The ministry said the aggressive actions, launched in parallel with the Pakistan-mediated peace process, had exposed the US administration's bad faith.
The US military earlier said it had carried out strikes in southern Iran, targeting missile launch sites and Iranian boats that it said were attempting to lay mines in the Strait of Hormuz.
A spokesman for US Central Command (CENTCOM) said the latest "self-defence strikes" were aimed at protecting troops from threats posed by Iranian forces.
Israel and the US jointly went to war against Iran on February 28. A ceasefire has been in place since April 8. Nevertheless, there have already been several attacks by both sides around the Strait of Hormuz.
The latest attacks, as well as Israel's actions in Lebanon, are overshadowing ongoing negotiations, mediated by Pakistan, to end the war with Iran.
