How can i disable iTunes autoplay when bluetooth device is connected? I don't know exactly when it began but for few months i have problem with bluetooth speakers. When they connected to mac iTunes starts to play music from it's playlist. How can i disable this function?

Also when my mac is in sleep mode and bluetooth speakers are connected, mac suddenly wakes up and start to play music from iTunes.
This is a common issue on Mac. Here is the tutorials that works fine on my rMBP with OSX 10.11:

1) Open a Terminal Window 

2) Rename iTunes.app to MyiTunes.app 

3) Create a DoNothing.app using the AppleScript Editor 

4) Copy the DoNothing.app to the Applications folder

5) Connect a bluetooth device to get the "Where is iTunes?" window prompt and Select DoNothing.app as what to auto-launch instead of iTunes 6) Closing thoughts about updates etc.

Resource: https://discussions.apple.com/message/25425864#message25425864