The Venezuelan government of President Maduro denounced the US strikes, calling them "extremely serious military aggression". It said the US carried out attacks on the capital Caracas and the states of Miranda, Aragua and La Guaira.
Venezuela had reported 29,088 cases of COVID-19 as of Wednesday, with 247 deaths.
The incident comes at a time when Venezuela has been put under quarantine and social distancing to prevent the spread of the COVID-19 epidemic.
Guaido's international trip was the second time he'd flouted the travel ban.
Washington has long been accusing the Maduro administration of human rights violations and abuses in Venezuela.
Venezuela is also the victim of attempted coups, assassination plots and sabotage of key industries, such as oil and electricity.
Her comments came at the end of a three-day visit to the country on the invitation of embattled Venezuelan President Nicolas Maduro, who has been facing allegations of cracking down on political opponents amid rampant hyper-inflation and shortages of basic goods.
In the case of a failed assassination attempt against President Nicolas Maduro in August 2018, 38 people were charged and 31 of them were imprisoned.
The Trump administration has been focused on supporting Guaido financially since they first recognised him as Venezuela's official leader in January, seeing funding as key to stabilising the country and securing his leadership.
Guaido will aim to keep up the street pressure on the regime with a huge Mayday protest on Wednesday that he said would be "the largest in the country's history."
