In some cases, Naruto might try to reach out to the Sakura he knows deep down. He could try to remind her of their past together, their training, and their shared experiences. He believes that the real Sakura would never do this, so he tries to break through whatever is making her act this way.
He could also try to dodge her attacks while still trying to reason with her. Naruto has a strong sense of loyalty and friendship, so he would likely be very reluctant to fight back against Sakura. He might keep asking her why she's doing this and try to get through to her emotional side.
Sakura may initially be paralyzed by fear, but then her love for Sasuke and her own determination to survive could kick in. She might try to counter - attack in a non - lethal way, hoping to subdue Sasuke rather than harm him. She could also call out to their shared memories in an attempt to stop him from actually killing her.
Naruto might initially be shocked and confused. He has always considered Sasuke as a friend, so Sasuke's sudden attempt on his life would be a huge blow. He may try to talk to Sasuke first, to understand why he is doing this.
Naruto might initially be in denial. He's so used to having Sakura around and believing that they have a future together. So when she leaves for Sasuke, he might think it's just a temporary thing or that she's been influenced by something or someone. But as time passes and he realizes it's real, he would be deeply hurt. He might also start to question his own self - worth, thinking that he wasn't good enough for Sakura. And he might even try to win her back at first, but then slowly come to accept the situation and focus on his other responsibilities like being a ninja and protecting the village.
He could also get angry. After all, being misjudged like that is unfair. His anger could lead him to either lash out verbally at Sakura or he could leave the village in a fit of rage, feeling that he is not accepted even by his friends. This could then lead to a series of events where Naruto has to find his own way and Sakura realizes her mistake later on.
He might be really hurt. Naruto has always been an outcast and being called a demon again could reopen old wounds. So he could just stand there in shock and disbelief, his eyes wide with pain.
Naruto could also react with anger. He's not one to just take things lying down. If Sakura hurts him, he might lash out verbally. He could say things like 'I've always been there for you, and this is how you treat me?' expressing his frustration and pain. And then he might storm off, leaving Sakura to realize the impact of her actions.
It might be a misunderstanding. Suppose there's a false rumor or misinformation that Naruto is a threat during the test. Sakura, being over - zealous in protecting the village or the test's integrity, decides to take him out. For example, if she believes Naruto has been secretly compromised by an enemy and she has no other way to deal with it during the test situation.
She might be heartbroken. Sakura could initially be in shock and then fall into a deep sadness. She may blame herself for Naruto's leaving, thinking that she could have done something differently.
She might be shocked at first. Sakura is used to Naruto being more passive when it comes to her hitting him, so when he suddenly stops her, it could catch her off - guard.