Obama's remarks were made during a town hall meeting with young leaders in South Africa.
While not mentioning Trump by name, Obama's speech countered numerous United States president's policies, calling on people to keep alive the ideas that Mandela worked for, including democracy, diversity and tolerance.
As is often the case, Obama is echoing the sentiment of an intelligent, powerful woman who also happens to be his wife.
"I am not being alarmist, I'm simply stating the facts", Obama told a crowd of about 15,000 in Johannesburg.
Events have been planned throughout the year for the 100th anniversary of his birth, including a large concert in December in South Africa that will be headlined by Beyonce and Jay-Z and hosted by Oprah Winfrey and others.
Screenshot via ABC NewsIn a speech commemorating Nelson Mandela's 100th birthday, former President Obama condemned "strongman" politics and the rising tides of nationalism. "Strongman politics are ascendant suddenly", he said.
Former US President Barack Obama speaks during the 2018 Nelson Mandela Annual Lecture in Johannesburg. —AFP
Many found this speech to be a passionate condemnation of identity politics.
Archbishop Tutu, who won the Nobel Peace Prize for his efforts to end apartheid and reconcile South Africans, said: 'Good leaders make allowance for the fact that even they can be wrong, and they know when and how to say sorry.
Obama praised the diversity of the World Cup champion French team, and he said that those countries engaging in xenophobia "eventually. find themselves consumed by civil war".
Obama also lamented that "the free press is under attack" at a time when Trump routinely complains about his coverage by "the fake news". You can't do it if you insist that those who aren't like you because they're white or because they're male, that somehow, there's no way they could understand what I'm feeling.
Obama continued saying "utter loss of shame among political leaders when they're caught in a lie and they just double down and lie some more". But he added that it is "right for the U.S.to insist on reciprocity" when it comes to countries that are no longer poor, like China, suggesting the US should tell China to "stop taking intellectual property and stop hacking our servers".
"I believe what people are doing is a failure to take South Africa forward and want to blame the man who brought freedom", he added.
"I believe a world governed by such principles is possible", he said. "We've been through lower valleys". "So we're gonna have to consider new ways of thinking about these problems, like a universal income". "We're going to have to learn from the mistakes of the recent past". "On one occasion, he saw me across a street at a common event and waved to me and said -'I hope you remember me!' incredible humility and grace", wrote Big B. The megastar added one more note on his Instagram page and wrote: "Nelson Mandela 100th birth anniversary".
Donald Trump conference with Vladimir Putin stormed by protester
After the summit, Huntsman's daughter Abby - a Fox News host - was less charitable about the president's diplomatic efforts. Responding to a reporter's question after that meeting, Trump said the two had a "very, very good start for everybody".