The greenback slipped 0.23% to 26,080 at unofficial exchange points. The currency held at VND26,020 at lender Vietcombank.
The State Bank of Vietnam lowered its reference rate by 0.01% to VND25,631.
Globally, the US dollar held at a two-week high on Wednesday ahead of policy decisions from central banks, with the Federal Reserve widely expected to leave its policy interest rate unchanged while signaling the probability of any December move, Reuters reported.
Most of the dollar's peers were unmoved ahead of the Fed decision. The euro was flat at $1.1129, as was the British pound at $1.3307. Against the yen, the dollar oscillated between gain and loss and was last 0.1% weaker at 157.81 yen.
The kiwi dollar sank as much as 1.7% to $0.5585 after the Reserve Bank of New Zealand unexpectedly held interest rates at 2.75%.
The Australian dollar was 0.1% stronger at $0.7035 after the release of inflation data, which was 1.3% in the third quarter of the year, after 0.6% the previous quarter.