2 Chainz -- I Didn't Get Jacked in San Francisco, But I Did Get HIGH

2 Chainz did NOT get robbed at gunpoint, but he does give San Francisco marijuana really, really high grades ... this according to the rapper himself.

As we previously reported ... San Francisco PD says 2 Chainz got jacked yesterday when someone fired shots in a crowd that included the rapper and his entourage.

But 2 Chainz sounds like he's denying anything went down at all -- because he tweeted, "Rule #1 if a rapper gets robbed people usually post items that has been taken. Rings, chains, watch, money etc."

He also says, "Rule #2 if a rapper gets shot he usually go to hospital or dies."

Police told us 2 Chainz said he wanted to handle the matter himself ... so the denial seems to back that up.