The "Guardians of the Galaxy" star shared a shot of himself in the gym on Tuesday, December 3 to advertise his new partnership with bosses at e-commerce giant Amazon, for whom he has listed his favourite workout gear for fans to purchase this holiday season.
However, the Instagram image caught Momoa's eye for all the wrong reasons, as a plastic bottle featured prominently in Pratt's hand.
Commenting on the picture, the "Aquaman" hunk, who has launched a campaign to clamp down on the use of plastic, wrote, "bro i love u but wtf (what the f**k) on the water bottle? no single use plastic. come on."
Momoa's remark quickly hit headlines, and he subsequently posted an apology to Pratt for putting him on blast so publicly.
Alongside a snap of himself and his two kids posing with Chris, Momoa shared, "BRO you know my children and I are madly in love with you and I love everything you do.
"I'm sorry this was received so badly today I didn't mean for that to happen. I'm just very passionate about this single use plastic epidemic. the plastic water bottles have to stop i hope u make a reusable water bottle for amazon so we all can purchase. You're an inspiration to many I'm one of them (sic)."
He then promised to send Pratt a case of his Mananalu Pure Water, which comes in 100 per cent recyclable aluminium cans, to help his pal lead a more environmentally-friendly lifestyle.
Pratt has since taken note of Momoa's messages and has expressed his own regret at the photo, revealing the plastic bottle was a last-minute prop added to make him feel more at ease in front of the camera.
"@prideofgypsies Aquaman! You're completely right. D**mit," he replied. "I always carry my big gallon size reusable water jug around with me too. I even had it that day!!!
"If I remember correctly somebody threw that plastic bottle to me in the photo shoot cause I didn't know what to do with my hands! I never know what to do with my hands! So uncomfortable."
"For real tho (sic). Love you too buddy. My bad," he continued, before quipping about Aquaman's underwater world, "I don't want your home of Atlantis covered in plastic."
Pratt then concluded the note with a more serious message for his followers, adding, "Hear that kids? Reduce. Reuse. Recycle."