A fleet with MEMORY_KEY_MAKE_AGGRESSIVE and MEMORY_KEY_MAKE_HOSTILE in its memory will always attempt to fight the player in the fleet interaction dialog... even if all they have left are civilian ships, or worse, mothballed civilian ships. Possibly only one of those memory keys is needed, I didn't test.
Minimal save (no mods required to load) (https://www.dropbox.com/s/6atnw0sorehnedj/save_aggroTest_1585496065670607659.zip?dl=0). Touch the nearest Persean convoy to see the issue.
Memory flags were applied to fleet with the following code in console:
runcode Global.getSector().getCampaignUI().getCurrentInteractionDialog().getInteractionTarget().getMemoryWithoutUpdate().set("$cfai_makeAggressive", true);
Global.getSector().getCampaignUI().getCurrentInteractionDialog().getInteractionTarget().getMemoryWithoutUpdate().set("$cfai_makeHostile", true);