Ibrahimovic told broadcasters Discovery early in the week that Los Angeles Lakers player James and other athletes with similar engagements should rather stick to their sports.
But four-time NBA champion James insisted after a Friday victory over the Portland Trail Blazers that "I will never shut up about things that are wrong."
"I preach about my people and I preach about equality, social justice, racism, voter suppression ... There's no way I would ever just stick to sports, because I understand this platform and how powerful my voice is."
Ibrahimovic had named James "phenomonal in what he is doing" but added: "Do what you're good at. Do the category that you do. I play football because I'm the best at playing football, I'm no politician. If I'd been a politician, I would be doing politics.
"This is the first mistake famous people do when they become famous and come into a certain status. For me it is better to avoid certain topics and do what you're best at doing, because otherwise it doesn't look good."
But James also recalled that Ibrahomivic, whose parents are fromBosnia and Croatia, himself had complained about racism in his native Sweden several years ago in connection with his last name.
"It's funny he'd say that because I believe in 2018 he was the same guy who said, when he was back in Sweden, talking about the same things, because his last name wasn't a certain last name, that he felt like it was racism going on when he was out on the pitch," James said.