IntelliJ IDEA runs on JRE 6, and so does its SBT plugin.
If you need to use a more recent version of Java (and you should):
- Open the Preferences panel
- Go to the SBT section
- Tick the Use alternative JRE option
- Click the arrow on the right of the field to check if the IDE suggests the desired JRE
- If so, choose it.
- Otherwise, look for the path by yourself.
/Library/Java/JavaVirtualMachines/jdk1.7.0_09.jdk/Contents/Homeon my Mac.