The country's second-biggest carmaker by sales sold a total of 216,118 vehicles in July, down from 229,044 units a year earlier, the company said in a statement.
Sharp sales declines in China continued to affect monthly results, the company said in a statement, citing political tensions between Seoul and Beijing over the deployment of the Terminal High Altitude Area Defense system in South Korea.
China has taken measures against the sale of group travel packages to South Korea as part of its retaliations against the THAAD installation. Chinese campaigns against South Korean products also weighed on Kia's sales in the world's largest auto market.
Seoul and Washington have argued THAAD is purely aimed at countering missile threats from North Korea. But Beijing has opposed the system, arguing it could spy on its military.
Affected by the THAAD row, Kia's sales in China plunged 55 percent to 129,670 autos in the January-June period from 285,590 units a year earlier, the company said.
Domestic sales fell 0.9 percent year-on-year to 43,611 units in July from 44,007. And overseas sales declined 6.8 percent to 172,507 from 185,037 over the same period, it said.
In the January-July period, Kia's combined sales declined 8.9 percent to 1.54 million autos from 1.67 million last year, the statement said.
For the rest of the year, Kia said it will focus on improving profitability by launching new models such as the Stinger sports sedan and the Stonic subcompact SUV in overseas markets. (Yonhap)