Vietcombank sold the greenback 0.11% lower at VND26,100.
The State Bank of Vietnam lowered its reference rate by 0.08% to VND24,940.
The dollar dropped 0.34% to VND26,340 on the black market.
It has risen 2.15% against the dong since the beginning of the year.
Globally the euro jumped along with risk-sensitive currencies like the Australian dollar on Monday after President Donald Trump backed down from threatened 50% duties on European Union shipments from June 1, after the bloc asked for time to "reach a good deal," Reuters reported.
The dollar continued its slump against a broad swathe of currency peers as Trump's policy reversals, as well as his sweeping spending and tax-cut bill currently in legislation, turned investors off from U.S. assets.
The U.S. dollar index, which tracks the currency against six major rivals, sank 0.3% to 98.813, extending a 1.9% tumble from last week.