"We can't stop until we achieve our freedom. I'm on the streets with you, in mind and spirit," he said, according to tweets from his wife Lilian Tintori.
Tintori relayed her husband's words after she visited him on Sunday at a prison outside Caracas.
Lopez, a speaker and leader of the opposition, has been detained since 2014 after he was accused of terrorism and inciting deadly anti-government protests.
The family had been denied access to the prison for about 35 days.
His wife said Lopez was not aware of the political turmoil and mass protests happening across Venezuela in recent weeks until she filled him in about the unrest during her visit.
"He is good... He is fit and well. ... He is isolated. He resists. It is hard but he resists," Tintori said outside the prison.
Since April, opposition leaders have faced off with Maduro and his supporters, accusing him of imposing a dictatorship.
Anti-government protesters want Maduro to step down and want new elections to be held. The government has repeatedly blocked any attempts to oust Maduro from power by a referendum vote. It has also delayed local and state elections.
"This isn't (just) a dictatorship -- this is a repressive dictatorship," Lopez said, according to his wife.
Statues vandalized, women urge peace
Anti-government protesters across the country have taken to beheading or defacing sculptures and monuments dedicated to late Venezuelan leader Hugo Chavez.
On Friday, a group tore down a statue in Villa del Rosario, a town in the western state of Zulia, near the border with Colombia.
A group of people are seen on video destroying the statue depicting Chavez wearing a sash. They carried the statue and threw it to the floor several times until it broke into pieces.
The governor of Zulia, Francisco Arias Cardenas, condemned the destruction as an act of vandalism.
"Two hundred ninety-five years of history have been lost to ashes because opponents want to turn the country into ashes. They do not mind destroying it," Cardenas said at an event in the town square where statue was located.
"Those who trampled on the statue of Commander Chavez do not see that their parents receive the pension and are benefited by social missions," he said.
About 18 people accused of destroying the statue were arrested, local media reported
On Saturday, thousands of women took the streets of Caracas.
Women in white marched to mourn the victims of violent acts and to call for peace.
"We want to get to the Justice and Peace Ministry, to tell them we don't want any more repression, clashes, we don't want any more blood, any more injured. Stop shooting! Stop shooting!" Tintori told CNN en Español on Saturday.
While they walked offering white roses to security forces blocking their way, red-shirted women marched in a pro-government rally waving banners in support of Maduro.
The women's marches in Caracas were among several ongoing events planned across the country calling for peace.
Venezuela's death toll rose to 36 on Friday when a 20-year-old man died after being injured in Thursday's protests, the country's attorney general's office said in a statement.
Some deaths have been linked to both opposition and pro-government protests while others happened during acts of vandalism unrelated to the political unrest.