Eastern Cape ANC spokesman Mlibo Qoboshiyane said people would be supporting workers' exploitation if they continued buying South African-produced wine.
"Next time people binge on wines from the Western Cape, they must know that they support exploitation of black workers," he said.
Farmworkers in the De Doorns area went on strike a week ago in demand of a R150 daily wage and better working conditions.
Qoboshiyane said farmers could afford to pay the workers what they wanted.
"The South African wine industry is making a lot of money locally and internationally; therefore, the wage demands of the workers are realistic and can be met by the employers."
He said Western Cape premier Helen Zille was failing to back the workers because farm owners were financing the Democratic Alliance -- the party she leads.
"The people of the Western Cape deserve a better leader than Zille," he said.
Earlier, Zille wrote a letter to President Jacob Zuma, asking him to intervene in the crisis.
De Doorns municipal officials said on Tuesday that violent strike action had resulted in damage estimated at R500,000.
"Property damage has been sustained including the destruction of a packing shed, veld fires, damage to farming crops, burning of tyres in streets and throwing of stones," said municipal spokeswoman Anette Radjoo.
On Tuesday, a policeman had to be hospitalised after being hit on the head by a stone thrown by protesters. On Monday, 10 people were arrested for public violence and intimidation.