The governing body issued their warning after two players were banned for a total of 19 weeks for launching foul-mouthed attacks on referees.
Andrew Renwick, the Selkirk captain, was sent off for his offence in the tussle with Watsonians at Philliphaugh on the opening day of the season while, on the same day, the Morgan centre Dougie Russell received his marching orders for a similar verbal outburst in the away game against Perthshire.
They were suspended for nine and 10 weeks respectively.
Graham Ireland, an SRU spokesman, said: "We made it clear referee abuse is unacceptable and will not be tolerated. This was followed up with advice to referees and members of the independent disciplinary panel. Given that respect is one of our sport's core values, it is disappointing to see that these two individuals have not taken this on board. Hopefully these sanctions will acts a deterrent to others."