Robert Griffin III -- I Didn't Like Anti-Redskins IG Post ... It Was My Intern!!!

It's time for "BLAME THE INTERN" ... starring Robert Griffin III.

RG3 is doing some serious explaining/fingerpointing this morning ... after Instagram showed that his account "LIKED" an anti-Redskins post that someone had written yesterday.

The post in question was a rant by a Skins fan who said, "I don't regret the skins grabbing RG, I do regret having a sorry ass team owner and sorry ass front office who couldn't put a winning coaching staff together who could actually compete for a super bowl."

After people noticed that RG3 "liked" the post -- the QB went into damage control ... and posted his explanation.

"One of our interns who helps with Instagram liked the post. As soon as I was made aware of it, it was immediately unliked."

Griffin continued, "I did not 'like' that IG post ridiculing our team. I have not been social media active consistently for awhile now and am ultra-focused on working to get back on the field and trying to help this team."

So far, the I.D. of the mysterious "intern" has not been revealed ...