Vietcombank sold the dollar at VND24,270, down 0.31% from Monday.
The State Bank of Vietnam lowered its reference rate by 0.16% to VND23,915.
The dollar was stable on the black market at VND24,650.
It has increased against the dong by 2.28% since the beginning of the year.
Globally, the dollar was on the defensive and trading by multi-month lows on the euro and a handful of other major currencies on Tuesday, as investors expect U.S. interest rates to fall next year and see that as a signal to sell the dollar in anticipation, Reuters reported.
Moves were modest in early Asia trade, but the dollar index had dropped below its 200-day moving average on Monday as a rally in the yuan spurred another round of broad weakness.
The index, which measures the dollar against a basket of six major currencies, fell 1.9% last week alongside a big rally in U.S. Treasures, and lost a further 0.5% overnight to 103.44.
The euro touched a three-month high of $1.0952 on Monday, with a little help from European Central Bank governing member and reliable hawk Pierre Wunsch pushing back against market expectations for rate cuts as soon as April.