Suprise! The WWE is definitely interested in Rob Gronkowski -- AFTER he wraps up his career in the NFL ... this according to WWE superstar Mojo Rawley. 

Mojo appeared on the "TMZ Sports" TV show (airs Wednesday night on FS1) and told us how awesome it would be crushing inside the squared circle with Gronk ... his longtime best buddy. 

And with Gronk being such a natural during his 2 recent WWE cameos, we had to ask if Vince McMahon's company has taken steps toward locking him up full-time. 

Mojo fills us in and talks about A LOT more in the full interview tonight on FS1. 

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