It is usually depositors who find it hard to get US dollars from banks, resulting in long, winding queues outside branches.
But now money transfer agencies such as Western Union and local banks are finding it even harder to get dollars from their suppliers, which are usually South African banks.
Banks in SA have said they are "de-risking" their operations and have put Zimbabwe banks on notice that they will no longer be able to supply them with dollars.
The move is associated with US sanctions against 84 individuals and 56 entities in Zimbabwe, which were extended for another year this week.
Reserve Bank of Zimbabwe (RBZ) director William Manimanzi recently said the country was importing hard currency from SA, but this would end as South African banks tightened their policies.
"Due to de-risking issues, most banks in that country have given us notice that they can no longer provide us with the cash," he said. "This means that we must now provide the cash to our own banks. The only bank that was still giving us cash was FNB and just in December they told us that they will no longer be supplying us with US dollars."
Rand Merchant Bank, the parent company of FNB, did not respond to queries.
But hardest hit have been money transfer agencies including Western Union, Mukuru and World Remit, which rely on a steady supply from SA's banks for their clients.
RBZ governor John Mangudya told the Sunday Times the impact of the withdrawal of the supply of dollars was quite visible.
"Money transfer agencies have been gravely affected, while local banks have different avenues of importing money from their own suppliers," said Mangudya.
An executive at Western Union, who spoke on condition of anonymity, said the "de-risking" by South African banks was a huge challenge as they were the major source of dollars.
"Correspondent banks in the US are not comfortable in dealing with money transfer agencies due to perceived money-laundering or terrorist-financing risk," the executive said.
"As a result, South African banks ultimately closed the money transfer accounts to secure their relationship [with the US banks] and have stopped exporting US dollars to Zimbabwe."
According to RBZ figures, Zimbabwe has lost more than 100 correspondent-bank relationships globally over the years. Banks cutting ties in recent years include Germany's Commerzbank and Barclays Plc in London.
A correspondent bank is a bank in a foreign country that provides services on behalf of local banks. It can facilitate wire transfers, conduct business transactions, accept deposits, and gather documents on behalf of another financial institution.
Economic analyst Prosper Chitambara said the drying up of dollars from South African banks would be a heavy blow.
"This will worsen the current account. In the short term the move will exacerbate the [shortage] of US dollars, which will cause the exchange rate premium to widen, exerting an upward pressure on prices."
Chitambara saw little chance of improvement in the foreign currency situation in the short to medium term. "The kind of institutional reforms necessary to bring back confidence and mitigate the high country-risk factor take a bit of time to implement."
Western Union this week said it was engaging other banks in the region to import cash. "We are engaging other institutions and corporates in countries like Botswana as a way of importing cash," said an official privy to the details.
Political analyst Alexander Rusero said it would be hard for any international institution to offer Zimbabwe money. "There are no security measures in place to guarantee capital. Neither is there assurance that the injected money will not simply vanish."..