isPlayBackMode()

var bBail = false;
var bInit = false;

function main(){
	if (bBail == true){
		return;
	}
	if (bInit == false){
		if (isPlayBackMode() == true){
			debugPrint("Sorry. This script does not run in playback mode.\n");
			bBail = true;
			return;
		}
		bInit = true;
	} 
	//...
	//... 
}