The Department of Trade and Industry on Saturday said those donating relief goods or participating in relief operations should get their items directly from suppliers.
The advisory came as the government set purchase limits at supermarkets.
"Ang instruction diyan ni Sec. Ramon Lopez i-refer na sa supplier ninyo. Sila na ang bahala mag-usap. Doon na sila bumili," Trade undersecretary Ruth Castelo said on radio DZMM.
Castelo cited DTI memorandum 20-10, which sets a limit on the number of basic goods such as food, water, and disinfectants that customers can buy in supermarkets in a single visit.
In the same interview, SM Hypermarket general manager Arnold Daluz said its stores are still accepting purchases from bulk buyers "on a case-to-case basis" depending on the availability of an item.
This is particular to local government units and private donors who wish to donate goods to families reeling from a Luzon-wide lockdown.
"Kung LGU ang bibili hinihingan lang namin sila ng certificates that they have to buy a lot from us," Daluz said.
(If LGUs will buy we will just have to request a certification allowing them to buy in bulk.)
Under the enhanced community quarantine, businesses, except those providing basic goods such as food and medicine, are closed, with some employees unable to work due to the closure of mass transportation and some businesses.