Advances in machine learning (ML) algorithms, graphics processing units, and readily available ML libraries have enabled the application of ML to open software engineering challenges. Yet, the use of ML to enable decision-making during the software engineering lifecycle is not well understood as there are various ML models requiring parameter tuning. In this paper, we leverage ML techniques to develop an effective approach to classify software requirements. Specifically, we investigate the design and application of two types of neural network models, an artificial neural network (ANN) and a convolutional neural network (CNN), to classify non-functional requirements (NFRs) into the following five categories: maintainability, operability, performance, security and usability. We illustrate and experimentally evaluate this work through two widely used datasets consisting of nearly 1,000 NFRs. Our results indicate that our CNN model can effectively classify NFRs by achieving precision ranging between 82% and 94%, recall ranging between 76% and 97% with an F-score ranging between 82% and 92%.