Veteran journalist Peter Bruce said he will not stop writing about the Guptas, despite a picket by Black First Land First movement members outside his home on Thursday.
When asked if the demonstration had deterred him, Bruce said he "doesn't know how to stop doing what [he] does".
Bruce, who is editor-at-large at the Tiso Blackstar Group (formerly Times Media) said he felt like the picket was an attack on his freedom of speech.
He warned that if similar incidents happen to other journalists in the future, it may set a new precedent for South African politics that will be "hard to undo".
Approximately 20 BLF members gathered outside Bruce's home, accusing him of producing fake news and supporting White Monopoly Capital. It was allegedly one of the members who wrote "land or death" on his roller door.
The protest follows reports that a former Gupta employee, who now lives and works in India, has been apparently linked to a secret surveillance report on Bruce – the results of which were published on pro-Gupta websites. It included photographs of his family, and of him having lunch at a restaurant with friends.
Bruce responded in writing with a column in Business Day, The Price of Writing about the Guptas. It is believed this column sparked the demonstration.
"I thought it was a fairly up and down column. I'm not a friend of the Guptas as people already know. I'd be lying if I said it wasn't scary. I have been doing what I think is the right thing as a journalist for 45 years. I couldn't stop writing about it (the Guptas) if I tried," Bruce said.
"I was able to stand and talk to the people (BLF members) who were outside. In a way, I quite enjoyed hearing what they said because they are also South Africans and it is important to hear each other. However, doing it (protesting) outside my house this way was a rotten thing to do."
In a statement, the Tiso Blackstar group said they are appalled at the "attempted intimidation" of Bruce.
"It is an outright threat to journalism that we shouldn't laugh off as a handful of lunatics making noise, but rather part of a concerted campaign to intimidate that should be condemned in the strongest possible terms by anyone who supports the freedom of the press," the company said.
"We will not be bowed by these bullying tactics."