But key Maduro ally Russian Federation slammed European "interference" in the oil-rich but impoverished Latin American country, saying it was an attempt "to legitimize usurped power".
In all, countries that back Guaido as Caracas' new president are Austria, Argentina, Brazil, Britain, Canada, Chile, Colombia, Costa Rica, Denmark, Ecuador, France, Germany, Guatemala, Honduras, Latvia, Lithuania, Netherlands, Panama, Paraguay, Peru, Spain, Sweden and the United States. Critics have called that election a sham and the mainstream opposition boycotted it.
"Therefore, Guaido is the person we are talking to and we expect him to begin an election process as soon as possible".
"We must all stick together and speak as one until such time as the former President Maduro has stood down and allowed fresh, properly conducted free and fair democratic elections to take place", Duncan added.
Maduro has been called on to resign and let the country hold a new presidential election as his government has sidelined the National Assembly, held widely questioned elections, and overseen an economic crisis that has forced millions of Venezuelans to flee, mostly to other South American countries.
Maduro flatly rejected the demands in an interview with Spanish television, insisting he would not "cave in to pressure". "We believe there must be elections to validate the choice of Venezuelans".
"I'm with the Venezuelan people against regimes like that of Maduro, based on violence, fear and hunger", League leader Matteo Salvini said last month.
Maduro is supporting plans for a meeting of Latin American and European Union states in "Contact Group" talks in Montevideo on Thursday.
The Trump administration last week issued crippling sanctions on Venezuelan state-owned oil firm PDVSA, a key source of revenue for the country, which is experiencing medicine shortages and malnutrition.
After several years of opposition efforts to oust Maduro, Guaido declared himself acting president at a rally on January 23.
Trudeau, who has been personally involved in the crisis, spoke with Guaido by telephone on Sunday.
Canadian Prime Minister Justin Trudeau said he would formally recognise Guaido's chosen envoy as Venezuela's legitimate representative in Canada in a move his government called symbolic.
The embattled Maduro, whose years in power have seen Venezuela sink into an economic crisis that the United Nations estimates has led as many as three million Venezuelans to flee the country and brought on widespread food shortages, has refused to step down despite accusations that his country's most recent election was rigged.
Trump warned that military intervention remains "an option" for dealing with the crisis in Venezuela.
Earlier Sunday, Maduro addressed troops on military exercises in Venezuela's coastal northeast, calling on them for "maximum cohesion" a day after a top Air Force general publicly sided with Guaido. Tens of thousands of people thronged the streets of various Venezuelan cities on Saturday to protest Maduro's government.
The Lima Group's final statement out of Monday's meeting in Ottawa emphasized the group's "support for a process of peaceful transition through political and diplomatic means without the use of force".
He said he finds the worldwide endorsement of Guaido "problematic" but his main concern is the prospect of military intervention - something the USA, which is not a member of the Lima Group, has mused about.