While 19-year-old Thunberg did attend protests in Glasgow last year for COP26, she said she won't attend COP27, scheduled to be held from 6 November to 18 November in Sharm El Sheikh.
"The space for civil society is going to be extremely limited," she said. "It's important to leave space for those who need to be there. It will be difficult for activists to make their voices heard."
Public demonstration is effectively banned in Egypt and limit on accreditation and attendance badges for activists have been a point of contention at previous UN climate summits.
Thunberg rose to prominence in 2018 at the age of 15 by staging school strikes in her native Sweden, becoming the face of the youth activist climate movement.
During Sunday's event, she decried the "sustainability crisis" as a "crisis of information not getting through."
People are trying to find new methods because we realise that what we have been doing up until now has not done the trick. It's only reasonable to expect these kinds of different actions.Climate activist Greta Thunberg on Just Stop Oil activists throwing soup at Vincent van Gogh's 'Sunflowers'
Her book includes explanatory articles from over 100 climate experts, including renowned climate scientists Katharine Hayhoe and Michael Mann, as well as authors including Margaret Atwood.
"I wanted it to be educational, which is a bit ironic since my thing is school strikes," she said.
Asked to comment on recent protest actions by Just Stop Oil activists which saw them throw soup at Vincent van Gogh's 'Sunflowers' at London's National Gallery, Thunberg said, "People are trying to find new methods because we realise that what we have been doing up until now has not done the trick. It's only reasonable to expect these kinds of different actions."