Vietcombank sold its dollar at VND25,440, down 0.11%.
The State Bank of Vietnam lowered its rate by 0.02% to VND24,251.
The dollar went up 0.06% to VND25,615 at unofficial exchange points.
It has risen by 4.09% against the Vietnamese dong so far this year.
Globally Japan's yen scaled a six-week high on Thursday, spurring speculation of an official push, while the dollar nursed broad losses as markets prepared for U.S. rate cuts in a few months, Reuters reported.
The euro, which scaled a four-month peak overnight, hovered near that level at $1.094 and sterling was steady at $1.3007, just below the one-year top it had made in overnight trade.
The yen gained sharply on Wednesday and was up another 0.5% to touch 155.37 per dollar in the otherwise quiet early hours of the Asia session on Thursday.