Diddy's attorney, Marc Agnifilo, tells TMZ ... the suicide watch directive issued by MDC officials was merely a routine measure for "new, high-profile inmates."

Agnifilo noted he spent 6 hours Thursday with Diddy at the federal lockup and the music mogul turned criminal defendant was "not at all suicidal." In fact, Agnifilo says, Diddy was "strong, healthy, confident and focused on his defense."

As you know, Diddy was arrested Monday night in Manhattan after a federal grand jury indicted him on charges of racketeering conspiracy, sex trafficking by force, fraud or coercion and transportation to engage in prostitution.

Diddy has been held in custody ever since as Agnifilo and his team of lawyers fight to get him out of jail. But, two judges denied Diddy's requests for bail, siding with federal prosecutors who say the Bad Boy Entertainment CEO tampered with witnesses in the case while posing a danger to the community.

As for Brooklyn's MDC ... it's considered a notorious jail with prisoners living in sickening conditions.