(CNN) Swedish teenage activist Greta Thunberg did not win this year's Nobel Peace Prize but that didn't stop her from taking her call for greater action on climate change to Denver.

Thunberg headlined a climate rally and strike Friday at the Greek Amphitheater in Civic Center Park. Event organizers included the International Indigenous Youth Council and Earth Guardians.

"The older generations are failing us and the political leaders are failing us, but we will be watching and holding them accountable," she told the crowd to cheers and applause.

She blasted political leaders for their immaturity and inability "to tell it like it is."

"The people in power continue to ignore us... How dare they," she said.