a small group took part in a march across a glacier in the south of Chile
the mayor of Sydney in Australia tweeted to say that there were "at least 45,000" demonstrators, making it the biggest ever such march in the city
"In 10 years' time our children are going to say, 'Mum, did you know about this? What was everyone doing'?" said Kate Charlesworth, a doctor and mother, in Sydney.
"These climate changes affect us all and it is here, through mobilisation, that we show how united our countries are against those larger nations that continue to pollute and refuse to cut back," said Antolin Huascar, a Peruvian agricultural official marching in Lima.
Some of the demonstrators in Place de la Republique in Paris were apparently protesting against France's state of emergency, and have been disowned by the main organisers.
The order, banning public gatherings, was put into place after the 13 November attacks.
Many of those involved in the clashes wore masks or covered their faces. Candles from a makeshift memorial in the square were thrown at police.
Interior Minister Bernard Cazeneuve said 208 people had been arrested, of whom 174 are still in custody.
President Francois Hollande said it was "scandalous" that the clashes happened "where flowers and candles have been left in memory of those who were killed by the terrorists' bullets".
He added that the clashes had "nothing to do with those who protect the environment".
About 150 world leaders are due to attend the Paris talks including US President Barack Obama, China's Xi Jinping, India's Narendra Modi and Russia's Vladimir Putin.
Negotiations began on Sunday afternoon but the main talks start on Monday.
Mr Hollande says he hopes a deal can be achieved, but that it will not be easy.
"Man is the worst enemy of man," he said. "We can see it with terrorism. But we can say the same when it comes to climate. Human beings are destroying nature, damaging the environment."
UN climate conference 30 Nov - 11 Dec 2015
COP 21 - the 21st session of the Conference of the Parties - will see more than 190 nations gather in Paris to discuss a possible new global agreement on climate change, aimed at reducing greenhouse gas emissions to avoid the threat of dangerous warming due to human activities.