In the seventh inning against the Colorado Rockies, an individual ran onto the field to take a selfie with Acuna, putting his arm around the player before security personnel dashed over.
While security worked to pry the individual off Acuna, another individual ran onto the field and rushed toward Acuna, appearing to make contact with him and knocking him to the ground.
Acuna sat on the grass as security dealt with the individuals. He got up on his own power. Atlanta had just scored four runs to take a 9-4 lead before the incident happened.
Acuna did not appear to be injured because of the incident, smiling afterward and flashing a thumbs-up sign.
"I was a little scared at first," Acuna said through an interpreter. "I think the fans were out there and asking for pictures. I really couldn't say anything because at that point, security was already there and we were already kind of tangled up, but security was able to get there and everything's OK. We're all OK, and I hope they're OK."
Atlanta manager Brian Snitker was disappointed with the fans' choice.
"You don't want to see that happen, I know that," he said. "You don't know what they will do when they get out there. It's a scary situation."
Colorado manager Bud Black concurred. "That's disappointing, for me, that it happens, especially in our ballpark, in our town," he said. "That bothers me. It bothers me in general when I see it elsewhere, in all sports."
When asked further about the incident in his postgame news conference, Snitker said he didn't see it live because he was in the bathroom. When pressed if he'd seen something like that before, he added, "Yeah, a bunch."
Kevin Pillar started in left field for the Braves on Monday, and was right near the incident when it occurred.
"I don't think they had any ill intentions. I think that was pretty evident early on," Pillar said of the two fans. "We have these rules and regulations, we're supposed to feel safe on the field. And thankfully, they weren't there to do any harm."
Acuna is one of the favorites for the National League MVP award this season. He entered Monday batting .330 with 28 home runs and 74 RBIs and had a standout game in the win.
Out of Atlanta's leadoff spot, he hit his 29th home run of the season and finished 4-for-5 with five RBIs and a walk in his club's 14-4 victory.
"Special player. He is a gifted young man, baseball player," Snitker said. "Anything he is going to do in this game is not going to surprise me. I just think he is that talented."
The Associated Press contributed to this report.