Martellus Bennett Not Interested In Replacing Gronk, 'I'm Retired!'

Sorry Patriots fans ... the guy who filled in for Rob Gronkowski in 2016 ain't interested in doing it again in 2019 -- with Martellus Bennett telling TMZ Sports he's retired for good.

Bennett -- who had 5 catches for 62 yards in the Super Bowl that season -- announced his retirement from the NFL in March 2018.

But, that was BEFORE Gronk decided to hang up his cleats ...

Remember, it was just back in February Marty joked about rejoining the Cowboys during a monster workout session in the gym. Dude still looks like he can play!!

So, when we spotted Marty B out in NYC Friday afternoon, we had to ask if he would consider putting the jersey back on for another stint with Tom Brady and Bill Belichick.

The long story short ... the 32-year-old says his mind is made up -- and it's a hard no.

"It's not me, I'm not the one," Bennett told us.

Instead, Bennett tells us he's focusing on his multimedia production company -- he's doing everything from book publishing to animated features and more.