The Animatrix may have had that line, but it was first said by Morpheus in The Matrix.

Morpheus: You’ve been living in a dream world, Neo. This is the world as it exists today… Welcome.. to the desert.. of the real. We have only bits and pieces of information but what we know for certain is that at some point in the early twenty-first century all of mankind was united in celebration. We marveled at our own magnificence as we gave birth to AI.

Neo: AI? You mean artificial intelligence?

Morpheus: A singular consciousness that spawned an entire race of machines. **We don’t know who struck first, us or them. But we know that it was us that scorched the sky. **