Get feedback on the unintended impact you have on others. There is often a gap between your intention (what you're trying to say or achieve) and the affect it has on others (how they experience what you're saying or doing). Ask a few people whom you trust to give you honest feedback and share how they experience you--especially under stress.
You might say, "I understand that some people experience me as hard to approach, especially when I'm under stress. I believe that's true, and I want to change it. Can you share with me what you've noticed that I might not be aware of? It would help me become a better manager and colleague." And then, when they do give you feedback, thank them. Being more approachable will help your team members communicate with you.