The 42-year-old revealed that it was pointed out to him that he shouldn't have been posting the photos amid the SAF-AFTRA strike.
"The last couple of days I foolishly and thoughtlessly let a trip down Suits memory lane distract me from the very real and ongoing fight everyone in @sagafstra continues to wage in its effort to win out membership realistic 21st Century compensation and protections," he wrote.
"It was an embarrassing oversight for which I'm incredibly sorry. So grateful to those who gently and swiftly course corrected me here and I look forward to continuing the fight in the days and weeks ahead."
The SAG-AFTRA Strike website states that members shouldn't share "photos, videos" or any "social media posts" that may "promote struck work or struck companies".
"This includes work done in the past. Streamers and networks are directing fans to past content to fill the void resulting from the WGA and SAG-AFTRA strikes," it adds. "Your influence carries weight with your fans. Let’s stand in solidarity together now to promote our cause so that we can promote each other’s projects in the future after we’ve won a fair contract."
Suits has been sitting at number one on Nielson's weekly streaming rankings for 11 weeks despite wrapping up in 2019.
Patrick starred as Mike Ross on the show, who was in a relationship with Meghan's character Rachel Zane.
The actor shared several photos of Meghan and his other Suits co-stars, including Sarah Rafferty.
"I miss my friends," he captioned the behind-the-scenes snaps, with the actor sharing more the next day, adding, "The well is deep."
In one snap, Meghan lounged on a couch, another was a close-up black and white portrait of the royal, while a third saw her lying on the floor, her feet up on a cabinet while Sarah sat on a couch, both women looking at the photographer.
Fans loved the photos, with many speculating the show may be returning.
"OK, I'm convinced Suits is coming back because this can't just be nostalgia," one user wrote.
"It can't be a random throwback right? Surely has to be a Suits reunion or something," another added.
"Don't give us hope," a third wrote. "Is Suits coming back?"
The Duchess of Sussex left the show in 2017, when she began dating Prince Harry.
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