"From the bottom of my heart, I am so so sorry. I don't have words," she wrote.
In a letter posted to his Twitter account and retweeted more than 4000 times, American film producer and father-of-three Patrick Millsaps offered Grande words of advice about self-care.
"Dear Miss Grande, I am the father of three daughters - ages 13, 12 & 12. So, you have been a part of our family for years," he began.
"Since you are a part of our family and after reading a tweet you posted on the Twitter the other night, I'm afraid I need to set you straight girl. So listen up and receive some redneck love from a daddy of daughters.
"You are no more responsible for the actions of an insane coward who committed an evil act in your proximity than you would be for a devastating natural disaster or acts of morons near your hotel."
Millsaps says Grande should not push herself to stick to her tour schedule. Although her shows until June 7 have been cancelled, her management have said that the tour is "suspended until we can further assess the situation and pay our proper respects to those lost".
Millsaps said Grande should listen to her own gut and not the "experts" around her.
"In your line of work, you have so many experts who are now 'strategising' what you should do next. These 'experts' don't have a freaking clue what you are processing right now.
"Spend time with your God, your family and your friends who will give you space and support when you need it.
"When and only when you are ready, SING AGAIN. Music is the international language of peace. Every time you open your mouth and share that incredible God-given gift to the world, you make this crappy world a little less crappy."
Saying it was "unsolicited advice from a fat dude in Georgia who loves his daughters", he signed off with one simple instruction: "Take care of you first. Your fans aren't going anywhere."
