President Obama urged a group of young Britons to reject isolationism and xenophobia at a town hall event in London on Saturday, encouraging them to embrace change rather than run from it.

“We see new calls for isolationism or xenophobia,” Obama said. “We see those who would call for rolling back the rights of people…they are reactions to changing times and uncertainty. But when I speak to young people, and I implore them and I implore you to reject those calls to pull back.”

He added, “I’m here to ask you to reject the notion that we’re gripped by forces that we can’t control.”

The president’s remarks come just one day after he weighed in on the United Kingdom’s upcoming vote on leaving the European Union, speaking out against the so-called “Brexit.” At a joint press conference with Prime Minister David Cameron, Obama said the U.K. is stronger as a part of the E.U. and hinted that leaving could have an adverse impact on trade with the U.S.

On Saturday, Obama pitched over 5o0 young people on the importance of inclusion and the opportunities global youth are currently afforded. “Progress requires the harder path of breaking down barriers and building bridges and standing up for the values of tolerance and diversity that our nations have worked and sacrificed to secure and defend,” Obama said.

The president’s words come as concerns grow over terrorism and immigration across the globe, amid a burgeoning refugee crisis and recent attacks in Paris and Brussels. British Prime Minister David Cameron has pledged to take in 20,000 Syrian refugees by 2020 and 3,000 refugee children within the same time period.

Obama’s primary message on Saturday, he said was to “reject pessimism and cynicism,” answering one attendee’s question about the difficulty of accepting slow change by urging patience.

“If any of you begin to work on an issue that you care deeply about, don’t be disappointed if a year out things haven’t been completely solved,” Obama said, noting that even the election of America’s first black president has not eliminated racism in the country.

The president also met with Labour Party Leader Jeremy Corbyn, where he congratulated the leader on his win and discussed the “impact of globalization on labor” and “the need to take steps to reduce inequality around the world,” according to a report on the meeting. He later engaged in a round of golf on Saturday with Prime Minister Cameron, who he is scheduled to have dinner with on Saturday evening alongside U.S. Ambassador to the U.K. Matthew Barzun.

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