Iranian Foreign Minister Abbas Araqchi said on Sunday a Ukrainian attack on an Iranian commercial vessel, "cannot go unanswered".
Iran said the attack in the Caspian Sea resulted in an explosion that killed one sailor and injured another.
Araqchi made the comments in calls with EU foreign policy chief Kaja Kallas and Russian Foreign Minister Sergei Lavrov, Araqchi posted on social media.
Lavrov, in a statement posted on the Russian Foreign Ministry's website, offered condolences in connection with the death of a sailor in the attack.
Lavrov said Araqchi thanked local authorities in the Russian region of Astrakhan, where the vessel started its journey, for helping the crew, "and stressed the need to put an end to such adventures by the Kyiv regime".
The statement also said Araqchi informed Lavrov of "continuing diplomatic efforts aimed at de-escalating tension in the Middle East".
(Reporting by Yasmine Ghania; Editing by Kevin Liffey and Nia Williams)
