The Portuguese boss was fuming as he confronted Cerra, who is in charge of analysing the team's opponents, by pointing at his tactics book.
The exchange came after Paul Pogba expressed confusion over an alteration in Zorya Luhansk's setup before United's 1-0 win at Old Trafford.
After the match, Mourinho told reporters: "It was set pieces, organisation, they changed their team before the game. Paul was a bit confused with the changes. Obviously, I want my assistants to take care of all the details."
United created just two shots on target during the match.