Hi, I'd like to help you with your question.
Making a speech when facing potentially hostile audience members can be unnerving. No one wants to feel they are opening themselves up to criticism from others who already harbor bad feelings towards them. But there are things you can do to make it an easier experience and maybe even win over your adversaries.
First, know who you are talking to. Giving a speech to people on the street is different than giving it to a group of executives interested in a certain product. Knowing who you are talking to and accounting for the diversity in the audience is important. You want to appeal to everyone on their level. Avoid talking down to them. Try to establish a connection by appealing to who they are rather than just providing facts and figures. Share a joke or two (practice this before hand with friends or family) and keep your tone light but knowledgeable.
Next, be mindful of what you are saying. You want to be clear about the purpose of the speech and the points that need to be made. Respect your audience's intelligence but don't talk over their heads. You want your information to be informative yet understood by everyone in the room.
Third, use your body language to convey openness and friendliness. You want your listeners to feel you are approachable. This includes the audience members who do not like you. Keep in your mind a feeling of forgiveness. Try to use your speech and gestures as a way to say you may not like me but I like you and we can be friends. That sounds corny, but if you can think it, your body language will follow your thoughts.
Fourth, keep your speech to the required length. Nothing says control and anger like someone who doesn't respect other people's time.
Fifth, be prepared. This will help your confidence more than any other point. The more you prepare, check your facts, and practice, the more confident you will be. Go over your speech until you feel you know at least parts of it by heart. Practice in front of anyone who will listen. Practice in front of a mirror. See how you come across. Ask others how you seem. Accept the criticism and adjust your mistakes. If you can, talk to experienced people on tips for giving a speech. Try out a Toastmasters meeting, if they are offered in your area (or try on line if not).
Lastly, talk about your fears. Accept that is ok to feel fear. Facing your fears is what gives you power over them. Many of the most experienced speakers I know talk about how they still experience butterflies before talking. They have used the butterfly feelings as a way to know they are prepared and energetic about their speeches. The more you can talk out your fears, the better you feel for facing them before hand.
Also, consider having people in the audience you are friends with. People who really like you. Focus on giving the speech to them. This will help you feel you have an ally instead of just enemies.
I hope this has helped you,