He captioned the photo: "The pic (sic) from yesterday... For those who wanted the show... For all the angels that love dad bod regardless..."
Alongside another image of himself in a fitted black T-shirt, he admitted he had been bombarded with questions about his figure instead of his work as he promoted his new movie, The Last Witch Hunter.
He wrote, "It is amazing the response from the journalists who I have been talking to for the last two days in New York. Today one wanted to see the dad bod. Haha... Body-shaming is always wrong!"
Diesel isn't the only celebrity to urge fans to stop criticising others over their bodies.
Model Gigi Hadid recently blasted Twitter and Instagram users for poking fun at her curves, while pop star Selena Gomez also previously confronted detractors who called her "fat", insisting she is proud of her figure.
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- WENN