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The army seized power on May 22 in a bid to end the crisis and kick-start the sputtering economy, but progress has been limited so far.
The economy suffered virtual paralysis in policy-making before the army took over. Badly hit sectors such as tourism are recovering only slowly.
Economists say there is a greater possibility of looser policy in the months ahead.
"The relatively soft momentum in the 3Q GDP report will add further weight to the argument that Bank of Thailand should ease again," said Benjamin Shatil, economist with JPMorgan in Singapore.
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"However, it is not clear to us that another 25 bp cut will have much of an effect in terms of stimulating activity, and we continue to look for government spending to support growth momentum into 2015, alongside a modest turn up in exports".
The central bank next reviews its policy rate on Dec. 17 after keeping it steady at 2 percent since March.
The National Economic and Social Development Board (NESDB) on Monday trimmed its 2014 growth forecast again to 1.0 percent from 1.5-2.0 percent. That would be the weakest growth since 2011, when devastating flooding cut growth to 0.1 percent.
But the agency revised up growth in April-June from the previous three months to 1.1 percent from 0.9 percent. The economy avoided a technical recession but the pace of recovery has been slow. In 2013, the economy expanded 2.9 percent.