So basically this macro was working fine as far as I could tell but recently it started acting up and I had to tweak it. The macro used to have /startattack in there but when I had a friendly player targeted to Intervene it would target the nearest unfriendly and what I would assume is prioritize the /startattack. So by removing /startattack it fixed that issue but I find myself still hitting that very button to start attacking. The thing I was wondering was, if it was possible to keep the /startattack in there and for the macro to just prioritize my target and not just override my target with the nearest enemy? The macro as it currently is:
#showtooltip Charge
(This is where I had /startattack)
/cancelaura Bladestorm
/cast [@mouseover,help][mod:shift,@focus,help][@target,help] Intervene;
/cast [@mouseover,harm][mod:shift,@focus,harm][@target,harm] Charge;
/cast [mod:shift,@focus,harm][@target,harm] Hamstring;
/startattack shouldn’t change targets if you already have one selected.
#showtooltip
/cancelaura Bladestorm
/startattack
/cast [mod:shift,@focus,help] Intervene; [mod:shift,@focus,harm] [@mouseover,harm,nodead] Charge; [@mouseover,help,nodead] [help] Intervene; Charge
/cast [mod:shift,@focus,harm] [] Hamstring
Hey Elven thanks again for you help, unfortunately I’m still having the same issue although it’s slightly different now. So I have the friendly player targeted and when I press the macro it intervenes as it should but then also immediately changes targets to the closest unfriendly, you’re definitely right about it not being /startattack though. Still I’m not too sure what the culprit is? possibly something to do with Hamstring? no idea… 
Edit So I just removed hamstring from the macro and it solved the issue so it’s definitely something to do with the ability.
you might try placing /startattack at the end of your macro instead
i have no logical reason why it should make a difference but it wouldn’t be the first quirk uncovered in the game
incidentally its where i place /startattack on my macros and it hasn’t been a problem for me
GL
Thanks for the reply smoke, this was one of the first things I had tried before and it didn’t yield any results, however upon further tinkering it now seems like /startattack is the issue and not hamstring. Starting to think this isn’t possible 
Ardreaver, that did the trick, it’s working how I wanted it to! thanks 
Edit Extremely grateful for everybody’s help!