"With great sadness and sorrow, we mourn the martyr of the nation and his duty, the righteous son Juma Mohammed Abdullah al-Kaabi, who gave his pure soul for the sake of humanity," the ministry said in a statement quoted by official news agency WAM.
The diplomats were expected to open a number of UAE-backed projects as part of an aid program in Afghanistan.
The Taliban denied carrying out the bombing, saying the attack was a result of "internal local rivalry," Al Jazeera reported.