I was born in the United Kingdom (Canadian parents) in London in 1994. I am now living in Canada and have a Canadian passport. Can I apply for a British passport?
You can only get a British Passport if you're a British Citizen. If you are one, then you need to follow the Gov.UK instructions on getting your first Adult passport. So, the question is, are you?
There's a very handy Check if you're a British citizen widget on the UK Government website. The answer is... Maybe. It all depends on the legal status of your parents in the UK at the time. If your parents were "Legally settled" (meaning they had the right to live permanently in the UK, also known as ‘indefinite leave to remain) at the time, then you would be. If they were just visiting temporarily, then the answer is no.
If not, if any of your grandparents was born in the UK (say, before moving to Canada), then you might be able to get a UK Ancestry visa. That would let you move to the UK, and start down the road to UK citizenship