A quiet word to an employee or aquaintance, suggesting that they'd best proceed with caution in respect of their current conduct or attitude, or they may be in for an unpleasant surprise. The details of which aren't actually set out by the giver of the warning, who may or may not have control over their fate.
The guy was certainly out of line, there probably wasn't sufficient grounds for disciplinary action, but he certainly got the gypsy's warning.