"789 bodies of migrants were recovered from the sea, including 102 Tunisians, the others being foreigners and unidentified people," Jebabli said, adding that more than 34,000 were rescued.
The North African country has become a major gateway for irregular migrants and asylum-seekers attempting the perilous sea voyage in the hope of a better life in Europe.
At its closest point, near Sfax, Tunisia is only about 130 kilometres from the Italian island of Lampedusa.
Between January 1 and June 20, a total of 34,290 migrants were intercepted and rescued, sharply up from 9,217 over the same period of last year, Jebabli said.
More than 30,000 of those rescued this year were foreigners, mostly from sub-Saharan Africa, he said.
Coastguard units carried out 1,310 operations in the first six months, more than double the number of missions year-on-year.
The Italian government says that more than 80,000 people have crossed the Mediterranean and arrived on its shores so far this year, mostly from Tunisia and war-scarred Libya.
The central Mediterranean has become the world's most dangerous migratory route, claiming more than 20,000 lives since 2014, according to the International Organization for Migration.