Mark Zuckerberg is setting a "dangerous precedent" by allowing a post by Donald Trump to remain on Facebook, a group of civil rights leaders has warned.
Their statement followed a video call with the social media giant's founder.
The US president's post, about the widespread protests following the death of George Floyd, was hidden by Twitter last week for "glorifying violence".
Facebook staff also voiced their anger at their employer, with some staging a "virtual walkout".
In the post, the president wrote he would "send in the National Guard", and warned that "when the looting starts, the shooting starts".
Mr Trump shared the same message on Twitter, where it was hidden behind a warning label, prompting an escalating row between Twitter and the White House.
Mr Zuckerberg had previously defended his decision to leave the same post up on Facebook, saying he disagreed with Mr Trump's words but that people "should be able to see this for themselves".
After meeting Mr Zuckerberg, three civil rights leaders responded that he was wrong.
"We are disappointed and stunned by Mark's incomprehensible explanations for allowing the Trump posts to remain up," they said in a joint statement.
"He did not demonstrate understanding of historic or modern-day voter suppression and he refuses to acknowledge how Facebook is facilitating Trump's call for violence against protesters.
"Mark is setting a very dangerous precedent for other voices who would say similar harmful things on Facebook."
The joint statement, released on Monday night, was signed by Vanita Gupta, president of the Leadership Conference on Civil and Human Rights; Sherrilyn Ifill, director-counsel of the NAACP Legal Defense and Educational Fund; and Rashad Robinson, president of Color of Change. It has been published online by Axios.
A Facebook spokesman said: "We're grateful that leaders in the civil rights community took the time to share candid, honest feedback with Mark and Sheryl [Sandberg, Facebook's COO].
"It is an important moment to listen, and we look forward to continuing these conversations."
Online therapy firm TalkSpace has pulled out of talks about a partnership deal with the social media giant over its decision to leave the post up.
"We will not support a platform that incites violence, racism, and lies," chief executive Oren Frank tweeted.
The deal would have been worth "hundreds of thousands of dollars" to TalkSpace, Mr Frank told CNBC.
In leaked audio, Mr Zuckerberg said his initial reaction to the Trump post was "disgust", reports The Verge.
"This is not how I think we want our leaders to show up during this time," he is heard to say.