Vietcombank hiked its rate by 0.04% to VND26,150.
The State Bank of Vietnam lowered its reference rate by 0.03% to VND24,955.
The greenback dropped 0.19% on the black market.
It has risen 2.34% against the dong since the begining of the year.
Globally the U.S. fiscal concerns and a tepid auction of Treasury bonds slapped the dollar to a two-week low versus the yen on Thursday, while President Donald Trump tried to push his sweeping spending and tax-cut bill through Congress, Reuters reported.
The dollar slipped to 143.27 yen early in Asia, the weakest level since May 7.
The euro was last flat at $1.1330, after rising 0.4% on Wednesday for a third straight session of gains.
Bitcoin pushed to a fresh all-time high on Thursday, partly as investors sought out alternatives to U.S. assets. Gold also benefitted, reaching an almost two-week top of $3,325.79 and putting it within $175 of April's record peak.