Four ambulance crews were attacked while attending calls on the Eleventh Night.
A spokesperson for the Ambulance Service said it was "completely unacceptable for both the personal injury caused and the disruption to ambulances available to respond".
The service was "stretched to the limit" on what proved to be a very busy night, with 447 emergency calls handled - up 21% from last year.
NIAS Chief Executive Michael Bloomfield said: “I want to express my sincere thanks, and those of the senior team, to them all for the commitment and dedication to duty which they have displayed tonight.
"I am aware that a number of our staff have been verbally or physically abused. I share the anger of our staff that these assaults continue to occur. Our staff are there for one purpose only - and that is to keep people safe."
Meanwhile thee Fire Service saw a "significant decrease" in the number of emergency calls due to bonfires in Northern Ireland.
Between 6pm and 1am, a total of 136 emergency calls were made, with crews responding to 91 incidents.
The Fire Service say 34 of these were bonfire related, representing a 40% drop in the number of incidents compared to 2018.
It is the lowest number of bonfire related incidents received by NIFRS since 2015.
The majority of bonfire incidents required limited intervention by fire crews, and there were no reports of attacks on crews or appliances.
The Fire Service say they maintained "normal service" throughout the evening and attending a range of non- bonfire related operational incidents, including a full emergency at George Best Belfast City Airport, a number of property fires and special service calls.