Sam Asghari is turning up the temperature and using his platform for something bigger than thirst traps ... and the internet is already sweating!

The actor and fitness stud just teamed up with MISTR, the nation's largest provider of free online PrEP and long-term HIV care, for a campaign that's equal parts steamy and seriously meaningful.

And the pics? Let's just say ... Sam understood the assignment. We're talking flexed arms, chiseled abs, and minimalist styling (yep, that towel is putting in overtime 👀) ... all giving fantasy shoot energy with a playful edge.

But it's not just eye candy. Sam's using the moment to push a bigger message ... helping normalize conversations around sexual health and HIV prevention.

MISTR's making that easy, offering PrEP and DoxyPEP completely free online ... no awkward clinic visits. And they're not small time either ... they now provide PrEP to about 1 in 5 users in the U.S., helping bring HIV prevention into the mainstream.

On top of that, Sam's been outspoken in support of LGBTQ+ rights in Iran ... where the risks are very real adding some real substance behind the sizzle.