"In a few days, an important meeting on climate change will be held in Paris... It would be sad, and I dare say even catastrophic, were particular interests to prevail over the common good and lead to manipulating information in order to protect their own plans and projects," he said ahead of the summit which officially starts on Monday.
"We are confronted with a choice which cannot be ignored: either to improve or to destroy the environment," he said in a speech at the world headquarters of the UN Environment Programme (UNEP) in the Kenyan capital Nairobi.
Francis, who is on his first visit to Africa, arrived in Kenya late on Wednesday with a warning that the world was facing "a grave environmental crisis" as he began a landmark three-nation tour which will also take him to Uganda and the Central African Republic.
The 78-year-old pontiff has taken on a vocal role in the fight against climate change, injecting a moral voice into a debate usually dominated by scientific, economic and political concerns.
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More than 150 heads of state and government are due to attend the start of the conference, which is due to wrap up on December 11.
Negotiators are to start talks on Sunday, a day ahead of schedule.
"COP21 represents an important stage in the process of developing a new energy system which depends on a minimal use of fossil fuels, aims at energy efficiency and makes use of energy sources with little or no carbon content," the Argentine pope said, stressing the need to rethink global models of economic development.
"For this reason, I express my hope that COP21 will achieve a global and 'transformational' agreement based on the principles of solidarity, justice, equality and participation; an agreement which targets three complex and interdependent goals: lessening the impact of climate change, fighting poverty and ensuring respect for human dignity.