He had asked the ministers of defence, military veterans, and police to give him a report on the situation there before making a decision on her request to call in the troops, she said in a statement.
"While I acknowledge that it would be prudent for the president to consult with the ministers, the situation in the affected areas has reached crisis levels and we cannot afford undue delays if we are to prevent the further loss of innocent lives," Zille said.
In a letter to the presidency last week, Zille asked Zuma to deploy soldiers to gang-ridden areas.
She asked for troops to be sent at once to Lavender Hill and Hanover Park, where there had been a "serious spike" in gang-related deaths.
At least 23 people, including seven children, have died in recent months.
In her letter, Zille said the deployment of the South African National Defence Force in gang hotspots over December had markedly improved safety levels.
Police Minister Nathi Mthethwa and Defence Minister Nosiviwe Mapisa-Nqakula were sent copies of the letter.
Mthethwa reportedly said the army did not have the equipment to fight gangsterism in Cape Town.
"The army doesn't have the equipment the police have: it doesn't have rubber bullets, it doesn't have water cannons," he said. – Sapa