BUENOS AIRES, Argentina—Argentina's Supreme Court rejected a proposal by the government to use a new legal regulation to get the top court to intervene in the case of a law opposed by the country's top media group.

The Supreme Court on Thursday rejected a legal mechanism that allows the highest court to step into cases even when they're being handled by lower courts.

The court also accepted an injunction shielding Grupo Clarin from the new media law, which would force it to disinvest and partially break up the company, the state news agency Telam reported.

Grupo Clarin had appealed a ruling by a lower court judge who said that some parts of the three-year-old law against media monopolies are constitutional.