Geralt was being jeered at by the residents of Blaviken after an event where he killed several men in self-defense and to prevent a greater massacre. It all began when he encountered Renfri's gang members, who had yet to act because she had gone alone to the tower to give Stregobor an ultimatum. Not wanting to risk innocent lives, Geralt fought the gang members and managed to defeat them all.
Shortly after, Renfri arrived and revealed that Stregobor didn’t care if she killed the entire village; he would not surrender to her under any circumstances. With no other options left, Renfri forced Geralt to fight her, which ultimately led to her death at the witcher's hands.
However, the people who witnessed the fighting didn’t understand the context of the situation or realize their lives had been in danger. Believing Geralt had attacked and killed without cause, they began throwing stones at him, thinking he was a murderer. While Geralt didn’t attempt to defend himself or stop them, you stepped in to protect him and put an end to the unjust attacks.