Christina Perri Stalker -- I'm Afraid Obsessed Fan Will Force Sex

Christina Perri is scared to death -- claiming an obsessed fan has been stalking her around the U.S., both in person and on the Internet, fearing he'll sexually assault her.

Perri -- whose big hit is "Jar of Hearts" -- just got a restraining order against Scott Brannan, claiming he's harassed and stalked her relentlessly for a year, despite multiple warnings to stay away.

Perri claims things have escalated so much, she now worries Brannan will commit "unwanted sexual acts" against her. She points to several comments on her YouTube page, like "I just want to love you, that's all, physically most of all." Doesn't sound ominous, but she clearly thinks so.

Perri claims Brannan has also gone out of his way to track down her brother and friends, writing them scary emails asking to see Perri face-to-face -- they all told Brannan to get lost.

Brannan has been ordered to stay at least 100 yards away from Perri at all times ... at least until a court hearing later this month.

8:20 AM PT -- For his part, Brannan tells us, Perri's accusations are 100% baseless. He says he simply reached out to her in the hopes of landing a date ... and he's not a bad guy. Here's his video response.