The MLS team said the accident occurred Sunday but declined to detail exactly how the 21-year-old Jamaican forward burned himself.
The team said he had been admitted to a local hospital and was "being assessed and treated."
"It was an unfortunate accident, but Darren is handling everything well and remains in good spirits," Whitecaps FC head coach Martin Rennie said in a release.
"We will have a better understanding on the recovery time and course of action later in the week, but we fully anticipate Darren to make a complete recovery in due time."
Mattocks joined Whitecaps FC in January after being taken second overall in the MLS SuperDraft.
Vancouver (1-0) hosts D.C. United (0-2) on Saturday.Suggest a correction