Vietcombank sold the dollar at VND24,740, down 0.04% from Thursday.
The State Bank of Vietnam lowered its reference rate by 0.06% to VND24,084.
The greenback was stable at VND24,600 on the black market.
It has increased by 4.26% since the beginning of the year.
Globally the dollar stayed on the back foot on Friday and was on course for a weekly decline against a basket of currencies as traders wagered that the U.S. Federal Reserve was most likely done with rate increases, lifting risk sentiment, Reuters reported.
The dollar index, which measures the U.S. currency against six rivals, was at 106.22, not far from the one-week low of 105.80 it hit on Thursday. The index is on course to clock a 0.3% drop for the week, just its third week of losses since July.
Analysts said any pullback in the dollar will probably be temporary, pointing to the strength in U.S. economy compared with the rest of the world.