If medium of studies is not in English, then its not acceptable unfortunately.
As I understand your degree certificate is written in English language, but your studies were not in English. I would advise not to use that, you wil have risk of misrepresentation on your application, perhaps depends on perception/understanding of immigration officer. If IRCC asks you to prove that medium was english, then it will be a problem. So, please take language test and submit.
From the Guide:
You attended a secondary or post-secondary education program in English or French, either in Canada or abroad.
A degree, diploma, certificate or official transcripts from a secondary or post-secondary education program showing you studied in English or French, in Canada or abroad.
If the original document is in a different language, include:
a letter from the school showing that the language of instruction was in English or French along with
an official translation of the original document and
the address and contact information (phone number) of the education institution