The feisty leader who is now the premier of the Western Cape province sparked a firestorm when she made the offending comment in March.
She wrote: "For those claiming legacy of colonialism was ONLY negative, think of our independent judiciary, transport infrastructure, piped water."
The party said the suspension was "decided by an overwhelming majority" and that sanction would remain until a disciplinary hearing was finalised.
"The suspension is effective immediately," said a statement.
The DA'S top executive said Zille's action had damaged the party.
"There is no question that Ms Zille's original tweets and subsequent justifications have damaged our standing in the public mind."
The party went on to say that Zille had "refused to take the appropriate action necessary to resolve this unfortunate and damaging matter."
On Saturday, DA leader Mmusi Maimane announced Zille's suspension, before backtracking to say a final decision would be made after she was given the chance to defend herself.
Zille who has a large twitter following is no stranger to controversial tweets.
Zille, 66, is credited with growing support for the DA among black people, whose votes helped it take control of key cities, including the capital Pretoria and Johannesburg, from the ruling African National Congress (ANC) after the local government elections last year.
South Africa, which was colonised by both the Dutch and British, remains deeply divided more than 20 years after the end of white-minority apartheid rule. The DA bills itself as an non-racial and equal opportunity party.
Disclaimer: No Business Standard Journalist was involved in creation of this content
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