Safari is frozen

so i was on my mac and this tab popped up and it says call this number (1-855-687-5874) to reslove any potential threats to my mac, now this has happened before but all the tabs allowed me to quit safari so i could restart my mac this one is different and wont let me restart my mac or quit safari, but i can use every other app on my mac except for safari, can anyone help? or do i just have to take this to my local appl store? thanks for any help