Unofficial exchange points sold the greenback 0.14% higher at VND25,770.
Vietcombank lowered its rate by 0.004% to VND25,454.
The State Bank of Vietnam maintained its rate at VND24,248.
The dollar has risen 4.26% against the dong since the beginning of the year.
Globally the yen hit an almost four-week high against the U.S. dollar on Friday, raising speculation that Japanese authorities may have intervened for a second day to prop up the currency, Reuters reported.
The rally in the Japanese currency, which has been languishing at around 38-year lows, began on Thursday just after data showed U.S. consumer prices for June eased, boosting the odds of the Federal Reserve cutting rates as soon as September.