Green is alleged to have sent the offending tweet to City Pages music editor Andrea Swensson in response to her negative review of his recent performance with Rihanna.
"I respect your criticism but be fair! People enjoyed last night!" Green tweeted. "I'm guessing your gay? And my masculinity offended you? Well f**k you! (sic)"
After realising he may have caused offence, Green - one of the coaches on The Voice - was quick to apologise for his perceived bigotry, and insisted he had meant no harm by the message.
"Apologies gay community!" Green wrote. "What was homophobic about that? I said I was guessing he was gay which is fine but it's nice to know what you think of me.
"I'm no bigot or homophobic, [It's] all a very big misunderstanding."
Only last week, 30 Rock star Tracy Morgan was forced to apologise after making several anti-gay comments during one of his stand-up shows.
Green has since deleted all of his Twitter messages related to the incident.