Unofficial exchange points sold the greenback at VND25,000, down 0.87% from Sunday.
Vietcombank maintained its rate at a three-week high of VND24,680.
The State Bank of Vietnam raised its reference rate by 0.03% to VND23,979.
The greenback has gained over the dong by 1.06% since the beginning of the year.
Globally the dollar was steady on Monday after data last week showing U.S. inflation remained sticky cast doubts on when the Federal Reserve would start its easing cycle, while the yen remained rooted near the psychologically key 150 per dollar level, Reuters reported.
The dollar index, which measures the U.S. currency against six major rivals, started the week down 0.058% at 104.14 after clocking five straight weeks of gains. The index is up 3% this year.
The yen has hovered around 150 level in the last few days, prompting officials to comment on the currency moves and keeping markets on alert to a possible intervention by Japanese authorities.