You can - but your application has to be processed by a visa office outside of Canada (either the visa office responsible for your home country or a visa office in the US). This means you must send your passport outside of Canada if you are approved for the study visa to be stamped. The application cannot be processed within Canada.
You should note that your chances of approval are lower if you apply while you are in Canada since it's more difficult to show ties to your home country.
