France will limit a UN climate summit in Paris starting in two weeks’ time to core negotiations and cancel celebrations after the attacks that killed 129 people, Prime Minister Manuel Valls said.

Valls said no foreign leaders had asked France to postpone the November 30 to December 11 summit, which aims to map out a global accord to limit greenhouse gas emissions. But he told RTL radio that “a series of demonstrations planned will not take place and it will be reduced to the negotiations... a lot of concerts and festivities will be cancelled”.

Climate change activists, however, reaffirmed their determination to hold a demonstration in the city on the eve of the summit, on November 29 – an event they hope will attract perhaps 200,000 people to put pressure on governments to cut greenhouse gas emissions.

We have to show to the terrorists that we are not afraid of them

Mainstream groups say they will respect any bans, decreed under emergency powers in France after the attacks on Friday that France blamed on Islamic State. French Foreign Minister Laurent Fabius, in Turkey for a meeting of the Group of 20, said many world leaders reaffirmed they would come to the summit. He quoted some leaders as telling him: “‘We not only planned to come, but now we have to come, because we have to show to the terrorists that we are not afraid of them’.”

Alden Meyer, of the Union of Concerned Scientists, said he did not think the attacks would affect the outcome of the climate conference, which is due to agree a plan to restrict greenhouse gas emissions beyond 2020.

“I don’t see these attacks having any substantial bearing on the substance of the negotiations, as opposed to Copenhagen, for example, where the 2008-2009 global economic crisis did raise doubts about the costs associated with climate action,” he said.

He and other experts also said the conference may also do more to discuss links between climate change and national security, a theme often stressed by US Secretary of State John Kerry.