Why are the Moroccans behaving this way!

Yes, Moroccans do hold a grudge against the Senegalese team, especially their allegedly corrupt coach and some of their supporters—not to say all of them, for trying to sabotage the Africa Cup final in Morocco.
Walking off the pitch because you disagree with the referee’s decision is the worst thing a team can do, especially for a team that had earned so much respect before that final.
On top of that, the Egyptian and Algerian staffs also did a great deal to undermine the organization of the Africa Cup, despite Morocco investing its heart and soul into hosting the tournament and making it a success for everyone.
Yes, Moroccans have the right to hold that resentment toward certain individuals from those countries (not their entire populations), because Moroccans are proud people who simply want justice to be served.
In this World Cup, they believe that, in the end, God’s justice prevailed.