Bad weather in Kazakhstan, where the oil is produced, and lower than expected output from the Kashagan oilfield at the beginning of the year contributed to the decline, said the official, who declined to be identified.
The Batumi terminal, operated by Kazakh state energy company KazMunaiGas , shipped 2.523 million tonnes of oil and oil products in the seven months, down from 3.163 million tonnes in the same period of 2013.
Shipments in July were 359,451 tonnes, down from 497,361 tonnes in July 2013 and 490,371 tonnes in June 2014.
The terminal shipped 5.63 million tonnes last year, up from 5.19 million tonnes in 2012.
Crude and refined oil products from Azerbaijan, Kazakhstan and Turkmenistan are shipped out of Georgia's Black Sea ports of Batumi, Supsa, Poti and the terminal in Kulevi.
Some products are shipped across the Caspian Sea in small tankers, unloaded in the Azeri port of Baku and then sent by rail to Georgian ports for export to the Mediterranean.