Guests became aware of the ban after staff refused the serve the beverage at event due to concerns about potential spills, as the drink contains a high number of colourants which can easily stain fabrics.
The property recently completed a £200m upgrade, which is reported to have included thousands of pounds being spent on refreshing the carpets.
Ralph Porciani, general manager at the Turnberry, said: “We can’t have it staining when to replace the ballroom carpet would be £500,000 alone. We have villas here with Irn-Bru stains in the carpets which I can’t let.”
Richard Leonard, the Scottish Labour leader who has pledged to lead the protests against Trump, said: “Someone who holds such misogynist, racist and anti-trade union views not to mention his whole approach to foreign policy, someone who rejects the Paris climate change agreement, should simply not be given the red-carpet treatment.”