NPA Spokesperson Koen Birkenstock said the risk of attack, together with the drop in the price of bunker fuel, was encouraging operators to sail via the southern tip of Africa rather than the Suez Canal and the Gulf of Aden.
Higher insurance costs and concerns over the safety of seafarers made it easier for higher-profile shipping companies to choose the longer route around the Cape, reports quoted him as saying.
Birkenstock said the country's ports would be able to deal with any extra demand.
He said Cape Town could offer a range of services to passing traffic.
"If there is an overrun [in Cape Town], ports such as Port Elizabeth, Durban and Richard's Bay can also provide services - such diversions would be dealt with by shipping agents," he added.
Maritime sources said passing traffic would not put pressure of cargo facilities.
“If they stop here, it would be for the convenience of bunkering,” said one.
The hijacking of a VLCC off the East African coast at the weekend highlighted the threat posed by pirates to international shipping.
Piracy off the coast of East Africa and the Gulf of Aden is estimated to have cost up to $30 million in ransoms this year.