People who think they're "politically woke" and who cast stones at others for petty mistakes need to get over themselves, according to former US president Barack Obama.

Speaking at the Obama Foundation's annual summit in Chicago, America's 44th leader was quizzed about the state of politics and activism in the country and the trouble with its growing 'woke' culture.

Being 'woke' — or being aware of and attentive to all the injustices in society — became somewhat of a catchphrase in the lead up to the 2016 presidential elections.

But Obama said those who believed being woke made them superior and untouchable were kidding themselves.

"This idea of purity and you're never compromised and you're politically woke, and all that stuff — you should get over that quickly," he said.

"The world is messy. There are ambiguities. People who do really good stuff have flaws. People who you are fighting with may love their kids and share certain things with you."

Obama said he was particularly concerned by young people thinking they could spark change by calling out people in power for petty mistakes, such as spelling and grammar errors.

"One danger I see among young people particularly on college campuses is that I do get a sense among certain young people, and this is accelerated by social media, that the way of me making change is to be as judgemental as possible about other people and that's enough," Obama said.

"Like if I tweet or hashtag about how you didn't do something right, or used the wrong verb, then I consider that I can feel pretty good about myself because, 'man did you see how woke I was, I called you out'," Obama said, prompting laughter in the crowd.

"That is not activism, that is not bringing about change.

"If all you're doing is casting stones, you are probably not going to get that far."

Michelle Obama said she felt a sense of injustice. Photo / AP

Former first lady Michelle Obama also spoke about the country's enduring problems with racism at the summit.

She shared that she grew up during a period of "white flight" where white families would move away from neighbourhoods as black families moved in.

"Families like ours — upstanding families like ours who were doing everything we were supposed to do and better — as we moved in, white folks moved out because they were afraid of what our families represented," she said.

"I always stop there when I talk about this out in the world because I want to remind white folks, ya'll were running from us. This family. This family with all the values you read about, you were running from us.

"And you still running, because we're no different from the immigrant families that are moving in. the families that are coming from other places to try to do better."

Obama said she still felt a "sense of injustice" but just tried to do the best she could for society.

"I can't make people not afraid of black people," she said.

"But maybe if I show up every day as a human, a good human, maybe that work will pick away at the scabs of your discrimination."