"I'm mad with love for Venezuela, for the Bolivarian Revolution, for Chavez and his example," he added, smiling as the crowd cheered, in a reference to former President Hugo Chavez.
Mujica, a fellow leftist who ruled Uruguay between 2010 and 2015, said on Wednesday he respected Maduro, but still thought he and others in Venezuela were "crazy" for attacking each other rather than sitting down to resolve problems.
Amid a deep economic crisis, Venezuela's opposition is pushing for a recall referendum to oust Maduro. Government officials say that will not happen this year, and security forces have been blocking protest marches demanding the vote.
Numerous foreign countries are calling for dialogue, but there is deep hostility and suspicion between Maduro's government and the opposition Democratic Unity coalition.