Joe Biden maintains “unequivocal” support for the Good Friday Agreement, a White House spokeswoman said.
Foreign Affairs Minister Simon Coveney earlier said the UK cannot be trusted over the Northern Ireland Protocol, which ensures the Irish border remains open and free-flowing.
White House press secretary Jen Psaki said: “President Biden has been unequivocal about his support for the Good Friday Agreement.
“It has been the bedrock of peace, stability and prosperity for all the people of Northern Ireland.”
The UK has unilaterally extended some grace periods of light-touch regulation on goods crossing the Irish Sea to Northern Ireland following lobbying by businesses.
Ms Psaki added: “We also welcome cooperation between our British and Irish partners on the Northern Irish protocol and the recent strong statements on these governments’ full commitment to the Good Friday Agreement.”
Before his election, the US president said the Agreement cannot become a casualty of Brexit.
The UK is presently seeking a bilateral trade deal with the US.
The US has agreed to suspend millions of pounds’ worth of tariffs on UK exports as part of an effort to resolve a transatlantic trade dispute over aerospace subsidies.
Washington will temporarily suspend tariffs on a range of goods, cutting the 25% tariff rate on Scotch whisky to zero percent for four months, according to the Department for International Trade.
Following a conversation last month, UK Prime Minister Boris Johnson sought to reassure Mr Biden – who is fiercely proud of his Irish roots – that he remained firmly committed to the Northern Ireland peace process.
Mr Johnson said then: “This is fundamental for us, the Anglo-Irish Agreement, the peace agreement, the Good Friday process, the Belfast Agreement, these agreements are absolutely crucial.”
Pressed on his support for the Northern Ireland protocol in the Brexit Withdrawal agreement following the recent row with the EU over vaccines, he replied: “We want to make sure that there’s free movement, north-south, free movement east-west, and we guarantee the rights of the people of Northern Ireland, of course.”
President Biden’s ancestral homes in Ballina in Mayo and the Cooley Peninsula in Louth celebrated his inauguration earlier this year with champagne and cake while waving Irish and American flags.
The US president’s proud links to Ireland are well known and often spoken about by the Democrat.
He is seen by many as the most Irish-American president to date.