A Labour MP close to Jeremy Corbyn has criticised the US's decision to impose sanctions on the Venezuelan president.
Chris Williamson said it would be "better to facilitate talks" between the government and opposition amid ongoing political unrest and violence.
The Labour leader is under pressure to condemn President Nicolas Maduro, after voicing support for him in the past.
Shadow foreign secretary Emily Thornberry said concerns of growing "authoritarianism" must be addressed.
More than 120 people have died during months of anti-government protests in the country.
Two opposition leaders who boycotted a controversial election to create a new constitutional assembly - denouncing it as an attempt by the government to strengthen its power - were put in a military prison on Tuesday.
A statement from shadow foreign minister Liz McInnes on Monday called on the government of Venezuela to recognise its responsibilities to protect human rights, free speech and the rule of law.
And a spokesman for shadow foreign secretary Emily Thornberry went further on Thursday, saying President Maduro had to address the international community's legitimate concerns "about his increasingly authoritarian rule".
"The election must not be treated as a mandate for further repression and violence," he told the Guardian.
Mr Corbyn is currently on holiday and not expected to make any comment until he returns next week.
But Mr Williamson, a close ally of the leader, told BBC Newsnight on Wednesday that "clearly it can't be right, can it - in a situation where there is a massive crisis in Venezuela - to impose sanctions on the country."
Under the sanctions, announced on Monday, US firms and individuals are banned from doing business with President Maduro.
"Surely it would be far better to try and bring the sides together, to facilitate talks and to encourage the right wing opposition to stop these protests on the streets," Mr Williamson added.
Venezuela's 30 million citizens are suffering shortages of food, basic goods and medicines.
Families of UK diplomatic staff in the oil-rich country have been temporarily withdrawn from the country as anti-government protests continue.
Foreign Office minister Sir Alan Duncan condemned the "disgraceful regime", adding: "If the United Nations were to apply sanctions, we would be part of that."
'Talk not guns'
Mr Corbyn has previously supported the Venezuelan government under both socialist president Hugo Chavez and his successor Mr Maduro.
As a backbencher Mr Corbyn attended a 2013 vigil following the death of Mr Chavez, hailing him as an "inspiration to all of us fighting back against austerity and neo-liberal economics in Europe". He also shared a platform with Mr Maduro in 2006.
Asked whether his political philosophy was closer to President Maduro's or Tony Blair's, Mr Williamson declined to answer but said: "When a government is doing good things, as they certainly were under Hugo Chavez...that's surely a good thing that we should celebrate."
But Graham Jones, the Labour MP who chairs the all-party parliamentary group on Venezuelan, said he expected Mr Corbyn to comment on the situation in the Latin American country when he returns from holiday.
"It's down to each individual what they say and when they say it," he told BBC Radio 4's Today.
"As far as the party's concerned, you know Liz has made this statement. I think it was published in all the press. I would have gone further and I think more needs to be taken."
The GMB union said it would continue to support the Venezuelan Solidarity Campaign, a UK-based organisation to which 18 unions are affiliated, as its purpose was to defend the rights of ordinary people.
"We need to see an end to the bloodshed, of course, we need to ensure the government respects human rights, but we must have talking and not more guns," the union's general secretary, Tim Roache, told Today.