It demanded that pressure be put on the Shia militant group, which has ministers in the Lebanese government, to ensure there was no repetition.
The protest follows Kuwait’s expulsion of 15 Iranian diplomats on Thursday over Tehran’s alleged links to those convicted.
The letter delivered by Kuwait’s ambassador in Beirut late on Friday said the emirate’s supreme court had found that “Hezbollah took part in contacts, coordinating meetings, paid funds and provided arms and military training in Lebanon” for the defendants.
It called on Lebanon to take “necessary measures to curb these disgraceful practices” by Hezbollah as it is a partner in the government, ambassador Abdulaal al-Quenai told the official KUNA news agency.
Unlike neighbouring Sunni powerhouse Saudi Arabia, Kuwait maintains diplomatic relations with Shia-majority Iran. Shias make up around one third of the emirate’s population. However, sectarian issues remain sensitive