In Indesign (on right click option), there is one menu called "Edit With". From this I can able to select the application from which the equations can be edited.
If you double click the equation its will open automatically in Mac "Preview applicaition" in Windows "Image Preview". Once you set the always open with (Change to all) the math type equation in Math type application only. After double click the equation its open math type then your setting is correctly.
You try this methods its working windows also mac. After you can open a euqation via script this line "app.activeDocument.links.editOriginal();"
Thanks csm_phil for your reply. This really helps me.
Also, could you do one more help.