According to a report in The Information, Zuckerberg told employees he was reluctant to bow to the threats of a growing ad boycott, saying "my guess is that all these advertisers will be back on the platform soon enough."
"We're not gonna change our policies or approach on anything because of a threat to a small percent of our revenue, or to any percent of our revenue," he apparently told the employees, according to the report on Wednesday.
Of the 25 largest spenders on Facebook ads, only three companies — Microsoft, Starbucks and Pfizer have confirmed pause ads on Facebook.
As Facebook ad boycott by more than 400 brands officially began on Wednesday, the social networking giant said it was getting better at removing harmful content and that the platform does not in any way profit from hate speech.
Writing an open letter to address concerns of advertisers, Nick Clegg, Facebook's Vice President of Global Affairs and Communications on Wednesday said that "platforms like Facebook hold up a mirror to society".
"I want to be unambiguous: Facebook does not profit from hate," said Clegg, who is a former Deputy Prime Minister of the United Kingdom.
The call to boycott ads on Facebook started after the social networking giant decided to allow controversial posts by US President Donald Trump to stay up.
Facebook said that when it finds hateful posts on Facebook and Instagram, it takes a zero tolerance approach and removes them.
Facebook saw its market cap eroded in billions as more big brands boycotted its platform against the unchecked spread of hateful and disinformation on its platforms.
American food company Chobani, drug maker Pfizer and software major SAP were among the latest brands pulling who joined Coca Cola, adidas, cleaning supply firm Clorox, Conagra (the maker of Slim Jim, Duncan Hines and Pam), fast food chain Denny's, Ford and Starbucks to pull their ads from the platform.
Facebook's digital advertising accounted for more than 98 per cent of the company's nearly $70 billion in revenue last year.