I hate this ai diplomacy...

[Tellos Athenaios]

If you don't want such form of 'diplomacy' to happen, then:
1) stay away from AI borders (make sure you don't share a border)
2) Don't be too small and weak or the big boys will think you an easy target (Baktria which gets invaded by AS)
3) Don't be too large and strong, else you're seen as a threat and you'll find the AI factions around you allying and attacking you at the same time regardless of previous wars or alliances (AS, or in this case you).

Or: play Casse, and hope the Eleutheroi don't invade too soon; and remember their splendid isolation.