French President Emmanuel Macron put climate change high on the summit's agenda, which also includes discussions on inequality.
Trump faces a tepid reception as anxiety grows over a global economic showdown and tension over trade, Iran and Russia.
The threat to what some call “the lungs of the planet” has ignited a bitter dispute about who is to blame.
“We cannot become accustomed to homophobia and racism on the pretext that we are in a football stadium," the French president said.
Video of President Donald Trump's daughter conversing -- or trying to -- with world leaders went viral.
“We will send him another, it is not a tragedy," said the French president.
Gérard Araud also called former President Barack Obama the “ultimate bureaucrat” and “a bit aloof."
A YouTube video calling the fire a "false flag" has nearly 100,000 views.
The president said he spoke with the Roman Catholic leader to offer his condolences over the destruction at the iconic Paris cathedral.
Emmanuel Macron vowed to make the fire-damaged cathedral “even more beautiful.”
The famed Paris cathedral sustained “colossal damage,” but its main structure and at least some of its treasured relics and artworks survived.
European Council President Donald Tusk confirmed in a tweet that an extension had been agreed to, but he did not disclose the date.
"Behind the negation of Israel's existence, what is hiding is the hatred of Jews," the French leader said.
Massive crowds gathered at rallies in cities across France a day after vandals defaced a Jewish cemetery with swastikas.
President Emmanuel Macron broke his silence to tweet his appreciation for the police overnight, but pressure mounted on him to propose new solutions to calm the anger dividing France.
Prized Paris monuments and normally bustling shopping meccas locked down and tens of thousands of police took position around France.
Weeks of fiery protest show that climate policy that ignores class doesn't work.
Three weeks of protests have left four people dead and were a massive challenge to Macron.