Former U.S. President Barack Obama urged people to unite against "nationalism and intolerance", arguing that amid greater global pressures, now is not the time to "hide behind a wall."
In his first public address since leaving the White House, Obama advocated the virtues of democracy and collaboration to an audience of tens of thousands in Berlin, Germany.
"In this new world that we live in we can't isolate ourselves, we can't hide behind a wall," he said during a celebration to mark the 500th anniversary of the Protestant Reformation.
The former world leader was joined by his German counterpart Chancellor Angela Merkel as they sat on a stage in front of the Brandenburg Gate and took questions from a panel, including a social worker, an actor and a teacher.
In a clear nod to rising nationalist sentiment across the U.S. and the EU, Obama said that globalization is not the enemy but should be embraced in order to fend off anti-democratic values.
"What we now have to recognize, because of globalization and because of technology, and the disruptions that have occurred … is that this (new world) order that has been created has to be updated and continually renewed, because there is a competing narrative of fear and xenophobia and nationalism and intolerance and anti-democratic trends."
He urged listeners to "rally against those trends that would violate human rights or suppress democracy."
"That is going to be a significant battle we have to fight," he said, just days after the U.K. was hit by the latest in a string of extreme Islamist attacks.
Obama also said that it was important for world leaders to take a global view and assist with supporting less developed countries.
"One way we can do a better job is to create more opportunities for people in their home countries.
"When we provide development aid to Africa or we are involved in conflict resolution in areas where war has been taking place, we make investments to try to deal with climate change and the displacement of farmers … Those things we do not do just for charity, not just because they are the right thing to do or out of kindness, but also because if there are disruptions in these countries, if there's conflict … in this new world that we live in we can't isolate ourselves, we can't hide behind a wall.
"It's important for us to see those investments as part of our own wellbeing as well as to the benefit of others."
Obama made his comments as incumbent U.S. President Donald Trump conducts the final leg of his first international tour since taking office.
He is due to meet Thursday with EU and NATO leaders to discuss matters including defense, trade and the environment.
Obama defended his healthcare reforms, which have come under continued scrutiny from Republicans and are faced with an entire overhaul.
He said he was regretful that he was not able to do more to provide universal healthcare to U.S. citizens, but added that he was proud of his work in extending provisions to a further 20 million people.
"Certainly I have some regrets that we weren't able to get everyone healthcare and obviously some of the progress that we made is now imperiled because there is still a significant debate taking place.
"But for those 20 million people there lives have been better and we've set a standard for what's possible."