Rasomware is a malicious software within the malware family that seeks an economic benefit behind, that is, it first attacks and infects the user's computer through a malicious url and later asks for a payment through it to disinfect their computer.
Surely some of you will remember the famous case of the «police virus» also known as ukask, in which the user in question was also accused of consuming child pornography for what he should pay a fine so that your equipment is not rendered useless.
In this case we see that according to Malwarebytes the Mac is not getting infected but it executes a Java code that loads 150 frames of the screen in question, over and over again to display the warning and the content of the alleged violation. 
In order to get rid of this if it happens to us we have two very simple options, one of them would be to force the close Safari with CMD + ALT + Esc to then press the Shift key while relaunching Safari and thereby stop page reloading. The other option would be to open the Safari menu and click on "Restore Safari", in this way we will eliminate all passwords, cache and browser history.
In itself, this malware, as I have already said, does not carry any real risk except for the user who decides to pay, since it does not attack the system but if it tries to deceive by all means by making people believe that the computer has been blocked when it really is not. Hopefully Apple do not delay in removing a security patch to cover this.
More information - Increase your security against signed malware