The Jambos announced on Thursday that they had entered a "critical" stage in their battle to pay off debts of £25million as well as financing tax and running costs.
The SPL has now slapped a transfer embargo on the club and warned further punishments could be handed down at a later date.
The league said in a statement: "The Scottish Premier League has been informed by Heart of Midlothian FC that the club has failed to pay a number of its players on time today. This is a Remuneration Default in terms of the SPL Rules and the Club is therefore subject to an automatic transfer embargo while that Remuneration Default continues.
"The actions also indicate a potential breach of SPL rule A6.21 and a disciplinary hearing will be convened in due course."
The Gorgie side need to raise a reported £500,000 to see the club through to the start of the new season.