Hennessey's Tavern in Dana Point, California, hosted a Cinco de Mayo event on Friday.
To celebrate the Mexican holiday, the bar set up an inflatable wall.
Anyone who reached the top received a "green card" which they could turn in for a free drink.
"Yep this is really happening. Disgusting," wrote Laycee Barragato Gibson, who posted photos online that went viral.
She told BuzzFeed News she wasn't surprised that others shared her reaction. "Immigrants make up the fabric of our society," she said.
Climbers at the bar event also wore sombreros, she said.
"The vast majority of immigrants who come here illegally are doing so in order to survive and provide a better life for their families. It is a very human response. To mock these people is deplorable."
People said the stunt played to stereotypes, and was offensive to the struggle actual Mexican immigrants face.
"Trashy, typical racist establishment exploiting Mexican history with a tasteless joke."
"The wall wasn't funny guys! This country is being torn apart, families being ripped apart.. completely classless!"
On the other hand, some people thought it was a big deal over nothing.
Owner Paul Hennessey said he doesn't support President Trump's plan for a border wall. "Our intentions were to create a dialogue and show how ridiculous that it is to spend tens of millions of dollars to build a wall and even infer that Mexico foot some or the entire bill and have their citizens build it," he said in a statement.
"This event obviously struck a chord with many of you out there and you and a number of you did not understand our intent," he continued. "I encourage all of you to take the time that you have spent posting on social media to spend an equal or greater amount of time writing your congressman or the President himself to express your concerns just as I have.
Thank you for your comments and let’s stop this wall from being built."
Hennessey did not apologize, and people were not having his explanation.
Barragato Gibson said she found Hennessey's statement to be patronizing, an attempt at an easy out from the criticism he received.
"Regardless of what his intentions were, this event was insensitive and made the Mexican community the butt of a tasteless joke," she said. "All he had to do was apologize and admit that he made a mistake-- but in the end I think his statement dug an even bigger hole for himself and his company."