Trump's reported description of African state, Haiti and El Salvador as "shithole countries" in a meeting on migration was "racist... disrespectful and humiliating," the office of Nicaraguan President Daniel Ortega said in a statement.
The Nicaraguan presidency expressed solidarity with countries and regional organizations that have slammed the derogatory term.
Those sharply criticizing Trump include Botswana, El Salvador, Ghana, Haiti, Nigeria, the 15-nation Caribbean Community, the African Union and the African Group of UN ambassadors.
Trump has responded to the outcry by telling reporters "I'm not a racist."
Two other senators from Trump's ruling Republican Party called the reports a "gross misrepresentation" amid some accounts that the president might allegedly have used the word "shithouse" instead of "shithole."
Emotions are running high in El Salvador, Honduras and Nicaragua as Trump's administration moves to cancel temporary protection given to tens of thousands of their compatriots in the US.