In a memo sent to 6,000 staff, most of whom are based in London, the bank advised that it had chosen not to register with the Electoral Commission as a campaigning organisation and, therefore, employees should refrain from campaigning for either side to make sure they don't breach the rules on permitted activities.
However, although Goldman Sachs has not registered as a campaigning organisation, it has previously donated £500,000 to the "In" campaign.
The memo sent to staff, which was obtained and first reported by Sky News, advised them "not distribute any material which could be seen as campaigning for either outcome or endorsing the messages of either campaign".
Under the rules of the referendum campaign period, companies who have not registered as a campaigning organisation must not spend more than £10,000 on certain referendum-linked activities between Friday (15 April) and 23 June, when the country will head to the poll booth to decide whether to stay or go.
The Goldman Sachs memo warned: "Breaches may result in legal and regulatory action against companies, company directors and officers, or senior managers who have authorised a breach of the rules."
Last week, Credit Suisse advised its staff to avoid discussions around the EU referendum, including declining to attend any client events where a Brexit might be a topic of conversation.
Meanwhile, last month, Bank of America banned its staff from saying "Brexit" in conversations with clients.