On Thursday, the actress vowed to join Friday protests at the Capitol "inspired and emboldened by the incredible movement our youth have created".
"She read the read the [Intergovernmental Panel on Climate Change] report and she realized that the crisis was barreling straight at us, like a train", Fonda said, "and looked around and people weren't behaving appropriately".
When Law&Crime asked for information on the arrest, Capitol police did not discuss it in particular.
She wrote on her website: 'I can no longer stand by and let our elected officials ignore - and even worse - empower - the industries that are destroying our planet for profit.
Along with Fonda, speakers at Friday's launch event preceding the civil disobedience included Keya Chatterjee, executive director of U.S. Climate Action Network; high school senior and climate striker Jerome Foster; author and activist Naomi Klein; Annie Leonard, executive director of Greenpeace USA; biologist and author Sandra Steingraber; and Kerene N. Tayloe, director of federal legislative affairs at WE ACT for Environmental Justice.
In a recent interview, the aging actress said she was inspired by children such as Swedish climate activist Greta Thunberg. "And that really hit me".
Online, Fonda was criticized for the move, with many calling her "Hanoi Jane", a nickname she picked up for her protests during the Vietnam War.
The arrest came after the Grace and Frankie star launched her "Fire Drill Fridays" civil disobedience campaign, demanding urgent action to battle climate change.
"I think every single human being has to say, 'What can I do to put this at the forefront?'" Fonda added.