Um, actually, this is quite incorrect.
Every enemy in Chrono Trigger is tied to an event trigger. Almost all of these can be avoided (although some are extremely hard to do). A lot of the enemies will walk around, and you can just run around them. Others involve avoiding certain points in the ground, but a lot you can just get by if you avoid the actual mobs themselves.
Also, there is a flee command. Hold both trigger buttons until all the party members turn to run. This is actually based on a timer that increments constantly as you run away (and continues to increment even during menus if the ATB is in Wait mode). So you can open the Tech Menu in Wait mode, then press both shoulder buttons until all your party members are facing away from the fight, then close the menu, and not only will you escape, you can pretty much guarantee that you can escape from any foe without ever being touched.