Vietcombank sold the greenback at VND26,200, down 0.07% from Tuesday morning.
The currency fell 0.04% to VND26,370 on the black market.
The State Bank of Vietnam lowered its reference rate by 0.01% to VND24,982.
Globally, the dollar and China's yuan were steady on Wednesday as teams from U.S. and China concluded trade talks in London, hinting at a thaw in a damaging trade war between the world's two largest economies but offering scant detail, Reuters reported.
The countries' officials agreed on a framework based on a trade truce reached last month in Geneva that would resolve China's export restrictions on rare earth minerals and magnets, and remove some U.S. export restrictions that were recently put in place.
The dollar firmed slightly in the wake of the news, pushing the euro down 0.07% to $1.141 and steadying at 144.91 yen. Sterling dipped 0.1% at $1.3483.
China's onshore yuan was little changed at 7.1873 per dollar, while the offshore unit stood at 7.1875.
An index that measures the greenback against six other currencies inched up 0.1% and last stood at 99.132.
Much of the year has been dominated by investors' unease over Trump's erratic policies. Despite a bounce back in U.S. stocks, the erosion of investor confidence is clearly reflected in the dollar, which is down more than 8% so far this year.