He was trapped for 25 minutes in a lift in the Vatican and had to be rescued by firefighters.
It appeared to be an electrical issue that caused the lift to stop as the pontiff said there was a "drop in tension".
He asked the crowd to applaud the Holy See firefighters.
Pope Francis also urged governments to show the "political will" to take drastic steps to deal with climate change and said it is time to abandon dependence on fossil fuels.
Francis issued the appeal in a message on Sunday, the start of several weeks of prayer by Christians to raise political awareness about pollution and exploitation of natural resources.
He also urged people to reflect on "thoughtful and harmful" daily decisions about consumption and "self-centred" attitudes towards Creation.
Francis said that at the UN Climate Action Summit later this month, "governments will have the responsibility of showing the political will to take drastic measures" to achieve as quickly as possible zero net greenhouse gas emissions and to limit the average increase in global temperature in line with the Paris climate accords.
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