Vietcombank sold the dollar at VND24,430, down 0.28% from Thursday.
The State Bank of Vietnam lowered its reference rate by 0.02% to VND23,915.
The dollar fell 0.08% to VND24,720 on the black market.
It has increased against the dong by 3.03% since the beginning of the year.
Globally the dollar languished near a more than four-month low on Friday ahead of a reading on a key U.S. inflation gauge due later in the day, which will provide further clarity on how much room the Federal Reserve has to cut interest rates next year, Reuters reported.
The greenback hit a five-month trough against the New Zealand dollar and a three-week low against the euro in early Asia trade, resuming its decline after a sudden bout of risk aversion in New York hours on Wednesday led to a selloff in U.S. stocks and a rise in the dollar.
The dollar index was on track for a weekly loss of about 0.8% and looked set to extend last week's 1.3% decline, after the Fed left the door open to rate cuts next year at its last policy meeting for 2023.