My computer indicated that it had a virus and to call 844-493-9076 or visit microsoft.com. Why am I being directed to MS when I have a Mac?

Because that message was written by a scammer. Choose Force Quit from the Apple menu, close Safari, and then launch it with the Shift key held down. If that doesn't work, temporarily disconnect the computer from the Internet.

If it continues to appear, click here and run Adware Medic. You may need to use a different web browser.

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Helpful Links Regarding Malware Problems

If you are having an immediate problem with ads popping up see The Safe Mac » Adware Removal Guide, remove adware that displays pop-up ads and graphics on your Mac, and AdwareMedic. If you require anti-virus protection Thomas Reed recommends using ClamXAV. (Thank you to Thomas Reed for this recommendation.) You might consider adding this Safari extensions: Adblock Plus 1.8.9.

Open Safari, select Preferences from the Safari menu. Click on Extensions icon in the toolbar. Disable all Extensions. If this stops your problem, then re-enable them one by one until the problem returns. Now remove that extension as it is causing the problem.

The following comes from user stevejobsfan0123. I have made minor changes to adapt to this presentation.

Fix Some Browser Pop-ups That Take Over Safari.

Common pop-ups include a message saying the government has seized your computer and you must pay to have it released (often called "Moneypak"), or a phony message saying that your computer has been infected, and you need to call a tech support number (sometimes claiming to be Apple) to get it resolved. First, understand that these pop-ups are not caused by a virus and your computer has not been affected. This "hijack" is limited to your web browser. Also understand that these messages are scams, so do not pay any money, call the listed number, or provide any personal information. This article will outline the solution to dismiss the pop-up.

Quit Safari

Usually, these pop-ups will not go away by either clicking "OK" or "Cancel." Furthermore, several menus in the menu bar may become disabled and show in gray, including the option to quit Safari. You will likely have to force quit Safari. To do this, press Command + option + esc, select Safari, and press Force Quit.

Relaunch Safari

If you relaunch Safari, the page will reopen. To prevent this from happening, hold down the 'Shift' key while opening Safari. This will prevent windows from the last time Safari was running from reopening.

This will not work in all cases. The shift key must be held at the right time, and in some cases, even if done correctly, the window reappears. In these circumstances, after force quitting Safari, turn off Wi-Fi or disconnect Ethernet, depending on how you connect to the Internet. Then relaunch Safari normally. It will try to reload the malicious webpage, but without a connection, it won't be able to. Navigate away from that page by entering a different URL, i.e. www.apple.com, and trying to load it. Now you can reconnect to the Internet, and the page you entered will appear rather than the malicious one.

MollyJaye wrote:

How do I report this? This scammer had control of my desktop and went through my files

In that case, your computer is compromised. It may have had malicious modifications to its system, and there is no good way to detect and remove such modifications. Anti-virus software will not do the trick. The only choice that will actually guarantee your safety is to erase the hard drive and reinstall everything from scratch. See:

How to reinstall Mac OS X from scratch

Once your computer's system is clean, it would be a good idea to change the passwords on any online accounts. If you have any financial information on your computer in unencrypted form, you should notify the financial institutions in question.

(Fair disclosure: I may receive compensation from links to my sites, TheSafeMac.com and AdwareMedic.com.)

MollyJaye wrote:

How do I report this?

I doubt that you can as I suspect your local authorities have no jurisdiction over the nationality of the individual you spoke with, but you might as well give it a try.

This scammer had control of my desktop and went through my files. He told us that we needed to purchase software to clean up files and provide security. Should I be concerned about my passwords?

As thomas_r. has told you anything is possible at this point. Your best bet would be to completely restore your hard drive from a backup taken before all this happened and to change all your sensitive passwords.