The US vice-president, Mike Pence, has repeated a veiled threat of military intervention in Venezuela, but Washington appeared increasingly isolated in its willingness to contemplate using force to oust President Nicolás Maduro.

European powers and some of Donald Trump’s key Latin American allies – all of whom have recognised the opposition leader, Juan Guaidó, as Venezuela’s legitimate leader – warned that they would oppose sending troops into the country.

Guaidó had for weeks insisted his movement was focused on peaceful, democratic change. But after the opposition failed in a weekend bid to defy Caracas and bring aid into the country, he called on the international community to “keep all options open”.

That hint at the use of military force won an enthusiastic response from hawks like US senator Marco Rubio, but sparked alarm elsewhere, particularly as Trump has previously mooted ordering an invasion.

Speaking at an emergency summit of regional leaders in the Colombian capital Bogotá, Pence renewed the threat of intervention, describing Maduro as “a usurper”, and calling for a global push to oust him.

“To leaders around the world: it’s time. There can be no bystanders in Venezuela’s struggle for freedom,” he said. “We hope for a peaceful transition to democracy, but as President Trump has made clear, all options are on the table.”

But beyond the US, few appear willing embrace the prospect of violence. In Latin America, there is a painful and bloody history of US interventions, and the terrible fallout from the 2003 invasion of Iraq is another deterrent to the use of military force.

An invasion would be complicated and bloody, with a strong chance of sliding into protracted civil war. Venezuela has armed forces that are more than 300,000 strong, thousands more members of pro-government gangs or guerrilla groups, complex terrain – and a government that still has some support from international partners including China and Russia.

Brazil’s vice-president, retired general Hamilton Mourão, said on Monday that under no circumstances would his country allow the United States to intervene militarily from Brazilian territory, even though the country’s rightwing president Jair Bolsonaro has previously vowed to do “everything for democracy to be re-established” in Venezuela.

Colombian president Iván Duque has also now ruled out intervention, according to sources in his administration. Chile and Peru were among other regional powers opposing military action on Monday.

There was similar concern across the Atlantic, where European nations including Spain and Germany made clear they considered the deployment of troops a line that should not be crossed.

“Not every option is on the table,” the country’s foreign minister, Josep Borrell, told the Spanish news agency Efe on Sunday, in a blunt rebuke to both Guaidó and US supporters of intervention.

The European Union’s foreign policy chief, Federica Mogherini, insisted there could be no military solution to a political crisis.

“The origins of the ongoing crisis in Venezuela are political and institutional, hence the solution can only be a political one,” she said in a statement. “We reiterate our firm rejection and condemnation of violence and of any initiatives that can further destabilise the region.”

Before the meeting of the Lima group of Latin American powers and Canada, Pence told Guaidó, attending as Venezuela’s interim president: “We are 100% with you.”

The Lima group also said credible threats have been made against the life of Venezuelan opposition leader Guaidó and his family, adding that President Nicolas Maduro was responsible for Guaido’s safety.

“We want to hold the usurper Maduro responsible for any violent action against Guaido, against his wife and against their relatives,” said Colombian foreign minister Carlos Holmes Trujillo, speaking on behalf of the group.

Pence said he would urge regional powers to freeze Venezuela’s oil assets and hand them over to Guaidó’s control. The opposition have reportedly already taken effective control of US-based refiner Citgo, one of the few remaining profitable assets of Venezuela’s state owned oil firm PDVSA.

Earlier that morning the US announced it had added four regional governors to an already long list of sanctioned Venezuelans, and Pence said that tougher measures were still to come.

“In the days ahead … the United States will announce even stronger sanctions on the regime’s corrupt financial networks. We will work with all of you to find every last dollar that they stole and work to return it to Venezuela.”

But much of Venezuela’s government and industry are already sanctioned, making it harder for Guaidó’s allies to ramp up financial pressure on the regime.