When i use the code:

WoWObject obj1= wManager.Wow.ObjectManager.ObjectManager.GetNearestWoWUnit(wManager.Wow.ObjectManager.ObjectManager.GetObjectWoWUnit());
              uint address = obj1.GetBaseAddress;

"wManager.Wow.Helpers.Interact.InteractGameObject(address, true, true);"  

The bot Target  the  monster then  autoattack.

How can  i target the monster  but not attack , just target the enemy. What api shoud i use.

Hello, if you play in legion, you can:

wManager.Wow.Helpers.Interact.InteractGameObject(address, true, true, true);

bool InteractGameObject(Ptr baseAddress, bool stopMove = false, bool skipWaitTime = false, bool leftClick = false)

Depending on what you want to do, it should also be possible to do:

ObjectManager.Me.Target = obj1.Guid;

 

15 hours ago, Matenia said:

Depending on what you want to do, it should also be possible to do:

ObjectManager.Me.Target = obj1.Guid;

 

I have tested this methord, bot can target then move and attack the obj.  I  just want target the obj whithout attack, have any other methord i can target the obj?

5 hours ago, jeste309 said:

I have tested this methord, bot can target then move and attack the obj.  I  just want target the obj whithout attack, have any other methord i can target the obj?

This method ONLY sets the target. If you have your bot set to grind and you are targeting the type of mob that you've set as a target, the bot might decide for itself to "start a fight". 
Try doing whatever you're doing in a quester or call Fight.StopFight() right after.