The painting of President Jacob Zuma with his genitals exposed undermined efforts to build a strong South African brand, the Black Business Council said on Thursday.
Brett Murray's "The Spear" eroded the country's capacity to grow the economy and fight unemployment, it said in a statement.
"The display of the offensive piece of pornography that masquerades as art, was an affront to the cultural beliefs and sensitivities of the majority of South Africans, who believe that depicting senior members or elders of the community in a demeaning light, is unacceptable."
The council regretted the defacing of the work, but said it would help the vandals, Barend La Grange and Louis Mabokela, with their legal defence.
"In particular, we will assist Mr Mabokela, who should further consider suing the Goodman Gallery for the brutality that he was subjected to at the hands of their security personnel."