A person is liable for the intentional tort of “assault” if (1) he/she acts intending to cause a harmful or offensive contact with the person of another or a third person, or an imminent apprehension of such a contact; and, (2) the other person is thereby put in such imminent apprehension.
An act intended to cause apprehension of an imminent harmful or offensive contact, which directly or indirectly causes reasonable apprehension of such contact.
So v. Shin, 212 Cal. App. 4th 652 (2013):
The essential elements of a cause of action for assault are: (1) defendant acted with intent to cause harmful or offensive contact, or threatened to touch plaintiff in a harmful or offensive manner; (2) plaintiff reasonably believed she was about to be touched in a harmful or offensive manner or it reasonably appeared to plaintiff that defendant was about to carry out the threat; (3) plaintiff did not consent to defendant’s conduct; (4) plaintiff was harmed; and (5) defendant’s conduct was a substantial factor in causing plaintiff’s harm.
Restatement (Second) of Torts § 21. Assault:
(1) An actor is subject to liability to another for assault if
(a) he acts intending to cause a harmful or offensive contact with the person of the other or a third person, or an imminent apprehension of such a contact, and
(b) the other is thereby put in such imminent apprehension.
(2) An action which is not done with the intention stated in Subsection (1,a) does not make the actor liable to the other for an apprehension caused thereby although the act involves an unreasonable risk of causing it and, therefore, would be negligent or reckless if the risk threatened bodily harm.