Quito said the country was seeking mediation to resolve the impasse, while Assange posted a picture of himself on Twitter wearing an Ecuadorian football shirt. "The UK should not permit itself to be intimidated by the Trump administration's public threats to "take down" Mr Assange", it said in a statement.
Speaking at a news conference in Quito, Espinosa said Assange was granted naturalization on December 12.
Ecuador will continue to protect Assange, but that he can't stay at the embassy indefinitely, Espinosa said.
The British government said earlier on Thursday it had refused a request by Ecuador for Assange to be given diplomatic status as part of the South American country's efforts to resolve his dilemma.
" 'There are well-founded fears we have about possible risks to his life and integrity, not necessarily by the United Kingdom but by third party states, ' Espinosa said". He has limited space in the embassy and faces arrest were he to leave the small apartment in London's Knightsbridge neighborhood.
If Assange had been granted a passport and Ecuadorian citizenship (or at least residency), they could have flown him to Ecuador under diplomatic cover at any time, at least in theory.
Ecuador's newly elected president Lenin Moreno has warned Assange that he must respect asylum conditions and refrain from getting involved in the affairs of other countries. The entry shows that the country issued the passport on December 21st, nearly three weeks ago - and more than two weeks before Espinosa asked for assistance in getting Assange out of their embassy.
June 2013: After a year at the Embassy, Assange fears there are fresh moves being put in place to extradite him.
However, media reports suggest there are attempts in Washington to have the investigation dropped if Assange offers proof on who was behind the Clinton leaks. He originally sought sanctuary in the embassy, fearing that if he was sent to Sweden he would be extradited to the United States over the Wikileaks case.