"What we hope is that dialogue can be possible, and that we avoid an escalation that would lead to the kind of conflict that would be a disaster for the people of Venezuela and for the region," he said at the World Economic Forum in Davos.
The United States, Brazil and other countries on Wednesday endorsed Guaido's declaration in repudiation of President Nicolas Maduro, as more protests rocked the economically strapped country.
"Sovereign governments have the possibility to decide whatever they want," the UN secretary-general said on a Facebook Live broadcast from Davos, AFP reported.
"What we are worried (about) with the situation in Venezuela is the suffering of the people of Venezuela," he said.
Guaido's declaration takes Venezuela into uncharted territory, with the possibility of the opposition now running a parallel government recognized abroad as legitimate but without control over state functions.
In a televised broadcast from the presidential palace, Maduro accused the opposition of seeking to stage a coup with the support of the United States, which he said was seeking to govern Venezuela from Washington.
"We've had enough interventionism, here we have dignity, damn it! Here is a people willing to defend this land," said Maduro, flanked by top Socialist Party leaders, although the defense minister and members of the military high command were absent. The office of Defense Minister Vladimir Padrino did not answer a phone call seeking comment.