Angelique should've done MORE to her, since Julia obviously was smitten.
If we think about it storylinewise, though, Angelique didn't often have much opportunity or inclinations to harm Julia - nor would it have been to her advantage.
When Cassandra first came on the scene, she was friends with Julia and obsessed with the Dream Curse. By the time she might have noticed that Julia hadn't exactly been entirely truthful about her relationship with Barnabas, Nicholas was also on the scene insisting in no uncertain terms that Cassandra focus solely on the Dream Curse - even going so far as to torture Cassandra. And soon thereafter she would have risked Nicholas' ire if she'd taken any steps against Julia because Julia was an essential part of Nicholas' plans for Adam. Not that Cassandra didn't court Nicholas' ire when it came to her attempt to kill Adam - but she saw killing Adam as an integral part of her deep and sole obsession to turn Barnabas back into a vampire. And by the time Nicholas took his revenge and turned Angelique into a vampire, she was even more under Nicholas' thumb and her only defiances involved satisfying her bloodlust with Jeff, using him to try to cure herself through the experiment, and making Barnabas hers by going after Barnabas despite Nicholas' insistence she stay away. Julia wasn't even a blip on her radar.
Angelique didn't next encounter Julia until 1897 - and then they were working together on Barnabas' behalf, so it would hardly have been to her benefit to harm Julia. And also, there was that little detail that only Julia's astral body was in 1897 and it was impervious to any attempts against it, as Petofi found out.
Angelique didn't encounter Julia again until Leviathans, and by then she had renounced her powers and wanted nothing to do with the Collinses. It wasn't until after she found out the truth about Sky that she rekindled them, and after doing so her obsession was revenge against the Leviathans. Having accomplished that, yes, she did turn her attentions back to Barnabas and she did cast a spell to break apart Barnabas and Maggie. But truthfully she didn't really have to attempt that because Barnabas' disappearance into Parallel Time was an even more effective breakup than even Angelique could have conjured up. And once Barnabas left the scene, apparently so did Angelique, possibly because no one had any way of knowing if Barnabas would ever return.
It wasn't until Angelique encountered Julia in 1840 that the perfect opportunity presented itself to harm her. And also, that Angelique was much more closely related to the Angelique of 1795/96 who lashed out at everyone around her. For the most part, the Angelique of 1897 and Leviathans had exhibited a much more mature persona.