A posting on the website of the US-based group, Revolution Muslim, told Matt Stone and Trey Parker they would “probably wind up like Theo Van Gogh”.
The Dutch filmmaker was shot and stabbed to death in 2004 by an Islamist angered by his film about Muslim women.
The website posted a graphic photo of Van Gogh who was killed by an Islamic militant over the movie that accused Islam of condoning violence against women.
The posting gave details about a home Stone and Parker reportedly co-own.
It also listed the addresses of their production office in California and the New York office of South Park’s broadcaster, Comedy Central.
“We have to warn Matt and Trey that what they are doing is stupid and they will probably wind up like Theo Van Gogh for airing this show,” warned the posting, written in the name of Abu Talhah Al-Amrikee.
“This is not a threat, but a warning of the reality of what will likely happen to them,” it added.
Al-Amrikee later told the Associated Press the posting was not an incitement to violence. It had been published to raise awareness of the issue and to see that it did not happen again, he added.
A Comedy Central spokesman said the network had no comment.
In the 200th episode of South Park broadcast last week, Muhammad appears several times inside a bear suit. The prophets of the other main religions are also depicted.
In 2006, Comedy Central banned Stone and Parker from showing an image of Muhammad in an episode that was intended to be part of a comment on the controversy caused by the publication of caricatures of the prophet by a Danish newspaper.
Muslims consider any physical representation of their prophet to be blasphemous and the caricatures sparked mass protests worldwide.
Meanwhile South Park beeped out the words Prophet Muhammad and plastered Wednesday’s episode with the word “CENSORED” after being issued a warning by the Muslim group.
The irreverent comedy show also substituted a controversial image seen last week of the Prophet Muhammad in a bear outfit with one of Santa Claus in the same costume.
It was not immediately clear if the move was a bid to tread carefully following the warning against the South Park creators, or if they were poking fun at the fuss.
South Park has a history of biting satire against politicians, celebrities and the media. The two Colorado filmmakers are known to often work on South Park until just before they air, enabling them to react to current events.
In Wednesday’s new episode, Jesus Christ was depicted watching pornography and Buddha was portrayed snorting cocaine.
According to US law enforcement officials, the federal government rarely prosecutes threat cases. The First Amendment of the US Constitution gives broad protections to free speech. — Reuters/BBCOnline.