Iran issued a second warning to Ukraine on Sunday following what Tehran said was an attack on a vessel in the Caspian Sea.

Iranian officials claimed the attack on July 25 triggered an explosion aboard the vessel, killing one sailor and wounding another.

"Any attack on Iran always comes with a cost, and that remains true today. The U.S. and Israel are well aware of this," Ebrahim Azizi, head of the Iranian Parliament's National Security Commission, said in a post on X.

"Ukraine, too, may soon come to understand that Iran does not let actions go unanswered," he added, warning that the list of those "who have miscalculated continues to increase."

Iranian Foreign Minister Abbas Araghchi also blamed Ukrainian President Volodymyr Zelenskyy for the attack and said earlier Sunday that the incident "cannot go unanswered."