If that is room remperature, there isn't much you can do other than cut the time your lights are on or maybe look into a filter that hangs outside the tank. I know the Whisper 10 Filters on my betta tanks hang inside the tanks and I'm sure they produce heat. Even with my room temp at around 73 or 74, my betta tanks stay around 78 or 79. I'm sure that is from thea filter heat as the lights are only on about 5 hours a day.
Edit: You could possibly put them on a lower shelf in the room since the air is cooler near the floor (hot air rises). I don't know how much difference that will make though.