BuzzFeed won't be accepting advertising money from the Republican National Committee, citing presumptive nominee Donald Trump as the main reason.

In a memo to employees on Monday, BuzzFeed CEO Jonah Peretti said the company was negating an advertising deal signed in April with the RNC. The deal was worth about $1.3 million, a source close to the situation told CNBC. The news was first reported by Politico.

"Since signing this advertising deal, Donald Trump, as you know, has become the presumptive nominee of his party," Peretti wrote. "The tone and substance of his campaign are unique in the history of modern US politics. Trump advocates banning Muslims from traveling to the United States, he's threatened to limit the free press, and made offensive statements toward women, immigrants, descendants of immigrants, and foreign nationals."

Peretti added that Trump's plans directly conflicted with BuzzFeed's employees doing their jobs. For example, banning Muslims from traveling to the United States would limit its journalists from reporting.

"We don't need to and do not expect to agree with the positions or values of all our advertisers," Peretti added. "And as you know, there is a wall between our business and editorial operations. This decision to cancel this ad buy will have no influence on our continuing coverage of the campaign."

The RNC did not respond immediately respond to requests for comment.

Disclosure: NBC Universal, which is the parent company of CNBC, has also invested in Buzzfeed.