The commission did not release a full analysis of the results. The opposition said it won the election by a wide margin, according to its own vote count. Pre-election polls had suggested a clear victory for the challenger.
Mrs Machado addressed thousands of supporters gathered in Caracas on Saturday from a truck carrying a banner that read “Venezuela has won.”
“We have never been stronger than we are today,” she told the crowd, adding, “The regime has never been weaker… It has lost all legitimacy.”
The opposition leader, who was blocked from running in the election, went into hiding for several days.
Earlier this week, Ms. Machado wrote in the Wall Street Journal that she and other opposition leaders were “worried about losing their lives.”
She was greeted with cheers of “Freedom, freedom” and several other opposition leaders followed her, but Ms Gonzalez did not.
In a separate video message, he urged supporters to “respond to the regime's attacks with hope, unity and peace.”
Venezuela's security forces have tried to suppress mass protests in recent days, with clashes with police leaving at least 11 people dead.
More than 1,000 counter-protesters were arrested.
The government is facing increasing international pressure. U.S. Secretary of State Antony Blinken said on Friday there was “overwhelming evidence” that Ms. Gonzalez won the election.
His intervention comes as the presidents of Brazil, Mexico and Colombia have all called on Venezuela to release detailed election results.
Other regional governments, including Argentina, Costa Rica, Panama and Uruguay, have also expressed concerns about the vote.
However, President Maduro has the support of allies such as Russia, China and Cuba.
He asked Venezuela's highest court to audit the vote count and confirm the results, allowing him to remain in power for six more years.
The opposition says the courts are in the hands of government loyalists who will delay the release of the tally. Mr Gonzalez boycotted the court proceedings on Friday.
