Iran's President Hassan Rouhani sent a letter on Monday to Kuwait's ruler, Emir Sheikh Sabah al-Ahmad al-Sabah, state media reported, a further sign that the two might be trying to defuse tensions between the Islamic Republic and the Gulf Arab states.
Iran and the Sunni Arab-dominated Gulf countries, notably Saudi Arabia, support opposing sides in conflicts in Syria and Yemen but, in January, Kuwait's foreign minister paid a rare visit to Tehran.
He delivered a message from the emir to Rouhani, describing a "basis of dialogue" between Gulf Arab states and Iran.
Iran's state news agency IRNA said Rouhani replied to the message in the letter delivered by Iran's ambassador on Monday.
Kuwait state news agency Kuna said al-Sabah received Alireza Enayati in his palace and "during the meeting a letter was delivered addressed to His Highness ... from Rouhani".
Neither news agency gave details of the letter's contents.
Rouhani visited Oman and Kuwait in February on his first visit to the Gulf states since taking power in 2013.
He said Kuwait was among at least 10 countries to have offered to mediate in Iran's escalating feud with Saudi Arabia.