Julian Assange used the Ecuadorean embassy in London as a "centre for spying", the country's leader has said.
Lenin Moreno also said no other nation had influenced the decision to revoke the WikiLeaks founder's asylum after what he called violations by Assange.
Assange's lawyer had earlier accused Ecuador of "outrageous allegations".
President Moreno - who came to power in 2017 - said of the decision to end Assange's seven-year stay in the embassy: "Any attempt to destabilise is a reprehensible act for Ecuador, because we are a sovereign nation and respectful of the politics of each country."
He added: "We can not allow our house, the house that opened its doors, to become a centre for spying."
On Monday, two left-wing German lawmakers, Heike Hansel and Sevim Dagdelen, and Spanish MEP, Ana Miranda, held a news conference outside Belmarsh prison, where Assange is currently detained.
They made a call for EU states to offer him asylum and prevent his extradition to the US.
Ms Dagdelen, who is a member of The Left party, said the EU should "take action" to protect the "persecuted political publisher and journalist".
Ecuador's president also made references to Assange's apparently poor hygiene following allegations made by Ecuador's Interior Minister, Maria Paula Romo.
Assange's lawyer, Jennifer Robinson, disputed the claims when she appeared on Sky's Sophy Ridge On Sunday.
"I think the first thing to say is Ecuador has been making some pretty outrageous allegations over the past few days to justify what was an unlawful and extraordinary act in allowing British police to come inside an embassy," she said.
She added that Assange's fears of a US extradition threat had proved correct this week.
Assange is expected to fight extradition to the US over an allegation that he had conspired with former army intelligence analyst Chelsea Manning to break into a classified government computer.
Assange, 47, already faces up to 12 months in prison in the UK after being found guilty of breaching his bail conditions when he entered the Ecuadorean embassy in 2012.
He made the move after losing his battle against extradition to Sweden where he faced allegations including rape.