It was Oscar Pérez's first public appearance since the attack.
He has been on the run since the incident, with the government accusing him of terrorism and of working for foreign powers.
Venezuela has been shaken by often violent protests in recent months and is in economic crisis.
Video footage shows Mr Pérez, 36, in the middle of a group of masked demonstrators mourning the deaths of those killed in the demonstrations.
He called for another general strike on 18 July against the government, a date he called the "zero hour".
Mr Perez also urged Venezuelans to back a symbolic vote organised against government plans to rewrite the constitution.
During the helicopter attack several shots were fired and grenades dropped on the Supreme Court. No-one was injured.
Mr Pérez was a member of the police force for 15 years.
Colourful details have emerged about his past, including an acting role in the 2015 film, Suspended Death, which tells the story of elite police officers rescuing the victim of a kidnapping.
More on Venezuela's turmoil
A rogue Venezuelan policeman who used a stolen helicopter to fire on government buildings has re-emerged at an opposition vigil.