Spokesperson Isaac Mangena said the SAHRC was looking into the matter on its own initiative, after Leanne Brown-Waterson and her partner Christelle were told they could not hold their wedding at Kilcairn, as the owner did not approve of same-sex marriage.
Mangena said: "It is very worrying that despite the progressive laws prohibiting violence or any form of discrimination against persons based on their sexual orientation, we still have incidents where gays and lesbians are discriminated against."
As part of its investigation, which was in its initial stages, the SAHRC would interview the couple and the owner of the wedding venue.
"While we have several other similar cases related to discrimination against gays and lesbians, for now this investigation will be dealt with separately."
Website shut down
Kilcairn, in the Riebeek Valley of the Western Cape, could not immediately be reached for comment and the venue's website appears to have been shut down.
Website Mambaonline reported that a number of people began campaigning against Kilcairn, and those associated with it.
Brown-Waterson was quoted as saying that the woman who rents and manages the wedding venue, as well as the caterers, Two Food Fundies, had received hate mail, despite the fact that it was the venue owner who would not allow the couple to marry there.
"Both parties are receiving hate mail, threats via correspondence and telephone, and are being asked to explain themselves to the public," Brown-Waterson told Mambaonline.
This condemnation was misplaced, however.
"Both are innocent parties, and being lambasted by the public in itself is a criminal act," she said.
She appealed to anyone who had done so to apologise.