South Africa's central bank believes US tariffs will only have a modest impact on the country's economic growth while leaving its inflation levels broadly unchanged, its governor said on Friday.

US imports from South Africa are now subject to a 30% duty - the highest rate in Sub-Saharan Africa - after Pretoria failed to agree a trade deal with Washington in time for US President Donald Trump's deadline.

President Cyril Ramaphosa spoke to Trump on Wednesday to try to speed up trade talks, after industry associations and the central bank governor previously warned the tariffs could cause tens of thousands of job losses.

But at the central bank's Annual General Meeting on Friday, Governor Lesetja Kganyago downplayed the economic fallout.

"Our preliminary assessment is that tariffs and the other uncertainties in the global economy are causing modest damage to growth while leaving inflation broadly unchanged," he told the bank's shareholders.

"The US is a large trading partner for South Africa, but it is not as important as Europe, China or the Southern African Development Community," Kganyago added.

The US accounted for roughly 7% of South African exports in June, smaller than China's 12% and Germany's 8%, data from the South African Revenue Service showed.

The central bank's latest forecasts factored in a higher tariff rate but that only moved its growth forecast for this year down by around 0.1 percentage points.

"This is a setback, but not catastrophic," Kganyago said, explaining that the relatively low growth of about 1% expected in 2025 was part of a broader stagnation trend in place for roughly a decade.

Echoing Kganyago's assessment, South African financial markets have performed well this week even as the tariffs came into effect.

ETM Analytics said in a research note that investors were confident that South African businesses would be able to find ways to mitigate the impact of the tariffs and pivot to new markets.