The sanctions follow a weekend of violence that broke out between security forces loyal to Maduro and a US-backed opposition attempt to deliver aid into Venezuela.
Once a rich oil nation, Venezuela now suffers from hyperinflation, as well as food and medicine shortages.
Maduro has continued to refuse the delivery of aid from the United States, calling it an attempt to gain power over his country.
"The tragic events of this past weekend have only steeled the resolve of the United States of America to stand with you, to stand with freedom-loving people in Venezuela," Pence told Guaido at the Lima group meeting in Colombia's capital Bogota.
Pence also urged other Latin American countries to freeze the assets of PDVSA, Venezuela's state-owned oil company, and to restrict visas for officials close to Maduro.
"Effective today, the United States will impose additional sanctions on regime officials, including three border state governors implicated in last weekend's violence and a member of Maduro's inner circle," he said, adding that the US stands with Guaido "100 percent".