Former Cosatu general secretary Zwelinzima Vavi and EFF leader Julius Malema are plotting to overthr.
Former president Nelson Mandela's family must not "besmirch" his name, Archbishop Emeritus Desmond Tutu said on Thursday.
"Please, please, please may we think not only of ourselves. It's almost like spitting in Madiba's face," Tutu said in a statement.
"Your anguish, now, is the nation's anguish -- and the world's. We want to embrace you, to support you, to shine our love for Madiba through you."
Tutu asked the family to dig deep within themselves to find the grace that Mandela and the country deserved at this time.
Mandela's grandson Mandla Mandela launched a scathing attack on his family on Thursday after the Eastern Cape High Court ordered him to give up the bones of his father and two other relatives.
On Wednesday, the court ordered him to return the remains of his grandfather's three children to Qunu from Mvezo, where he moved them two years ago.
The remains were those of Mandela's eldest son Madiba Thembekile, who died in a car accident in 1969; Mandla Mandela's father Makgatho Mandela, who died in 2005; and Mandela's first daughter Makaziwe Mandela, who died as an infant in 1948.
The bones were re-buried at a ceremony at a gravesite at Nelson Mandela's home in Qunu on Thursday afternoon.