Those sanctioned Monday are in addition to the dozens of current and former Venezuelan officials the US already has targeted.
The United States has asked the countries of the Western Hemisphere to suspend Venezuela from the 35-nation Organization of American States.
The Venezuelan government has refused to allow worldwide aid, alleging that would amount to foreign intervention.
The new sanctions continue a pattern of stepped-up USA measures on individuals connected to Maduro, who is blamed by President Donald Trump's administration for a deep recession and hyperinflation in OPEC member Venezuela that has caused food shortages and sent a flood of migrants into neighbouring countries.
Venezuela is planning to hold elections on May 20, with Maduro running for a second term.
"I am not sure how we will make that happen, but I know that we can't stop, " she said right after her speech during a conference organized by the Council of the Americas.
On Monday, the Venezuelan representative to the OAS, Samuel Moncada, rejected Pence's statements and attempted to show USA concern for the people of the region as hypocritical, citing the tens of thousand of Central America refugees who have lost their Temporary Protected Status (TPS) during the Trump administration, making them subject to deportation to countries where they face threats of violence and death.
The 20 companies - of which 16 are based in Venezuela - were used to launder illicit proceeds from the drug trade, according to the statement.
Maduro, himself subject to sanctions previous year, regularly laughs off Washington's disapproval and blames the U.S.
Haley's comments Tuesday followed Pence's own call the previous day for Venezuela's elections to be suspended.
Before his departure in February, former Secretary of State Rex Tillerson indicated that the Trump administration was considering blocking all sales of Venezuelan oil, a move that might present the final blow to both Maduro and the country's economy.
US oil major ConocoPhillips has moved to take Caribbean assets of PDVSA to enforce a $2 billion arbitration award, three sources told Reuters. The U.S. State Department has said not all political parties have agreed to the elections, limiting the ability of individuals to run.