The South African Chamber of Business (SACOB) said on Thursday its Business Confidence Index (BCI) slipped slightly to 99.5 in March from 100.5 in February.
"The BCI is experiencing a bumpy ride ... this current turbulent wave (declining confidence trend) is the fourth experienced since the beginning of 2005," SACOB said in a statement.
The business organisation said the economy was growing fast but that improvements in infrastructure were not keeping up with expansion, compounding capacity constraints.
"You can't talk about wanting to grow by 6 percent then not have proper infrastructure to accommodate that. If you want to grow fast you must see to it that your environment is conducive to that," said Richard Downing, SACOB economist.
The government has set a target of achieving 6 percent economic growth by 2010, and is embarking on a 416 billion rand, three-year capital expenditure programme to upgrade transport and energy systems.
Downing said the lack of a proper rail network and better roads for easy transportation of goods and efficient electricity provision were a source of frustration.
The main industrial and tourists centres, Johannesburg and Cape Town, have been hit by ongoing power outages as demand for electricity strains capacity.
"Some of these (constraints) carry considerable risk, and could have severe consequences if they are not timeously and appropriately addressed," he said.
SACOB said it was concerned about the political and economic crisis in Zimbabwe.
The economy of South Africa's northern neighbour is crumbling and political tensions are rising after police recently arrested and beat opposition leaders for planning protests against President Robert Mugabe's rule.
"The Zimbabwe situation is affecting business confidence and the political situation is affecting this economy. We're not denouncing anybody but we're saying it should be sorted out soon," Downing said.
Thousands of Zimbabweans cross the borders into South Africa everyday to flee inflation of more than 1,700 percent and unemployment or around 80 percent.
"Our porous borders cannot prevent continued inflow of people from Zimbabwe, which will have further consequences for ... unemployment and poverty in South Africa," SACOB said.
SACOB said timely planning to ease constraints before they become serious obstacles would lift business confidence in the economy.