The Facebook post is a black and white photo of the vice presidential candidate with a quote next to her image that alleged she wants to "take the guns first."
"Take the guns first. Go through due process second, I like taking the guns early," the quote reads.
Though the words are attributed to Ms Harris, they were actually spoken by the president.
During the meeting, Vice President Mike Pence explained a legislative action to Mr Trump that would essentially authorise the confiscation of weapons by way of court order from people deemed a danger to themselves or others.
Mr Trump said he wanted to go further.
"Or, Mike, take the firearms first and then go to court. Because that's another system, because a lot of times, by the time you go to court, it takes so long to go to court, to get the due process procedures. I like taking the guns early," Mr Trump said. "Like in this crazy man's case that just took place in Florida, he had a lot of firearms - they saw everything - to go to court would have taken a long time, so you could do exactly what you're saying, but take the guns first, go through due process second."
Mr Trump's words have also been incorrectly attributed to Representative Alexandria-Ocasio Cortez.
Right-wing social media has a history of lying about Ms Harris' words and stances on gun control.
Shortly after she was selected as Democratic presidential candidate Joe Biden's running mate, right-wing social media posts were claiming that she intended to use executive orders to begin gun confiscations in the US.
"If elected and you don't surrender your guns, I will sign an executive order and the police will show up at your door," the post claims Ms Harris said.
Vice Presidents can't issue executive orders, and Ms Harris never made the claim.
USA Today confronted the owners of the page who initially shared the post and asked why they were lying about Ms Harris. The page administrators said the post was a "hypothetical," despite it clearly attributing the quote to Ms Harris.
"Anyone with an understanding of how government works (which should be anyone of high school age and older) understands VP's can't do executive orders," the page owner said. "This is a hypothetical. Her public history of gun confiscation comments shows that if she assumes the role of president, which a lot of people see as a real possibility given wrestles with senility, this isn't that much of a stretch."
What Ms Harris actually said during the primary was that she would give Congress 100 days to make progress on sensible gun reforms if she were elected president.
"Upon being elected [president], I will give the United States Congress 100 days to get their act together and have the courage to pass reasonable gun safety laws. And if they fail to do it, then I will take executive action," Ms Harris said. "I will require that for any gun dealer that breaks the law, the ATF take their license."