President Donald Trump mocked a teenage activist who gave an impassioned speech at the United Nations urging world leaders to do more to combat climate change.

Swedish 16-year-old activist Greta Thunberg scolded the audience at the United Nations Climate Action Summit on Monday, repeatedly asking, “How dare you?” Thunberg said: “We are in the beginning of a mass extinction and yet all you can talk about is money. You are failing us.”

In a tweet late Monday, Trump says: “She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!”

Trump had spent only a few minutes at the climate summit, a centerpiece of this year's UN General Assembly schedule.

President Donald Trump breezed by the climate change summit , choosing to focus instead on religious persecution, an issue that resonates with his evangelical supporters.

Trump arrived in New York against a backdrop of swirling international tensions, including questions about his relationship with Ukraine, the uncertain future of Brexit, the US trade war with China, stalled nuclear negotiations with North Korea and a weakening global economy.

The president met on Monday with leaders of Pakistan, Poland, New Zealand, Singapore, Egypt and South Korea.

He will speak before the UN General Assembly on Tuesday, with his administration's desire for a collective response to escalating aggression by Iran high on the agenda.