The AbaThembu royal family called the meeting in Qunu where Mandela was buried on December 15 and "shared their concern" amid reports of internal strife and warring over his estate.
"We advised the family members to remain calm, respect the administration of the estate and ensure that all the assets remain where they are until the processes are finalised," said a statement.
The meeting held on Friday decided that elders must attend all family meetings "until further notice", it added.
Local media last week reported to squabbling over Mandela's estate and that his widow Graca Machel had faced rejection and abuse and was told to leave the Johannesburg home she shared with Mandela once he died.
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The royals threw their backing behind Machel who they said represented Mandela "in all matters of the Mandela family".
"Immediate family members must mourn and their actions must resemble the dignity that Madiba deserves," said spokesman Daludumo Mtirara, referring to Mandela's clan name.
Madikizela-Mandela earlier this month denied there was a dynastic battle within the extensive family.
But the Mandela family is no stranger to drama, with reports surfacing of a renewed feud shortly after the icon's funeral.
Earlier this year, a family court battle saw the remains of three of Mandela's deceased children ordered back to his boyhood village.