Vietcombank sold the dollar at VND24,630, up 0.06% from Sunday.
The State Bank of Vietnam kept its reference rate stable at VND24,089.
The dollar was unchanged at VND24,620 on the black market.
It has gained over the dong by 3.79% since the beginning of the year.
The dollar was on the front foot on Monday in cautious trade as tensions in the Middle East escalated, while investors awaited a speech by Federal Reserve Chair Jerome Powell later this week for further clues on the U.S. central bank's rate outlook.
Carry trades funded by the yen could be the biggest casualty of further escalation in the war, analysts said, as global investors who have for months been shorting the yen to invest in higher-yielding currencies buy it back as a safe-haven.
The yen was last steady at 149.53 per dollar.
The Japanese currency, which is near to potential intervention levels around 150, could also rally if the Fed has to stop hiking rates even as the Bank of Japan feels compelled by domestic inflation to tighten policy.
Elsewhere, the safe-haven dollar stood near a one-week high against a basket of currencies as risk sentiment remained fragile, pinning the euro near a one-week low hit on Friday.
The single currency was last 0.11% higher at $1.0522.