The statement said that the rescue operation happened about 50 kilometres to the southeast of Zarzis in Medenine province. The group is said to have consisted of 17 Sudanese nationals and one Egyptian national.
The statement added that it was confirmed that the immigrants had sailed from Libya towards the coast of Italy.
On Saturday, the government said that that it had thwarted two illegal immigration attempts involving 94 immigrants off the coast of Sfax. 58 Tunisians and 36 people of various African nationalities were arrested in the operation.
The summer season tends to coincide with a spike in illegal immigration attempts due to favourable weather conditions.
However, that does not make the journey any easier with Mediterranean Sea deaths in 2019 accounting for half of all global deaths recorded of migrants in transit, according to the International Organisation for Migration (IOM).
Over 600 people have died in 2019 while attempting to make the dangerous crossing across the Mediterranean Sea.
At least 36,670 migrants and refugees have entered Europe by sea through 24 July, according to the IOM, representing a 35 per cent decrease from the same period in 2018.