If your definition of grabbing is anything like mine, I hope you will try alternatives that teach mutual respect instead of overpowering your child. That will only work while he's small, and it sounds like it's already not working so well. This is a great time to re-evaluate your parenting techniques. One of the most important things I ever "got" as a parent and caregiver was the need to be consistently firm but gentle and respectful, because children learn FIRST from imitation and only second from our words.
I was a hands-on mom and am now a hands-on granny, but the only time I have ever "grabbed" a child was to avert a dangerous situation. Touching, holding, constraining, embracing are all gentle parental maneuvers. Grabbing, at least as I experience it, is a different category of forcefulness, suggesting anger, impatience, and lack of respect for the child's person.
The same is true of the tone we use with our children. There is a world of difference between telling a child "Please use a calm voice and tell me what you need," and, "You don't talk to Mommy like that." The latter is using the tone of voice you DON'T want your son to use with you or others, so there is a disconnect between example and instruction. I'm not sure how old your son is, but he is apparently still young enough to be defaulting to your example.
Are you hurting him? If fear is rising when you "grab" him, then he can very well be experiencing that as hurt, or fear of hurt. Whether or not this it true, if you want calm, compliant children, they need a calmly assertive mommy.
There are wonderful parenting books available to help you get there. Since my grandson was about 2.5, I've used the techiniques in How to Talk So Kids Will Listen, and Listen So Kids Will Talk, by Faber and Mazlish. He's now 5, and almost 100% of the time, he's a great team player and creative problem solver, respectful, cheerful and polite. He reflects the tone and attitudes of his parents and other adults in his life life.
I'm very much enjoying reading the books Playful Parenting, by Lawrence J. Cohen, PhD., and Parenting Without Power Struggles by Susan Stiffelman, which is appropriately subtitled 'Raising Joyful, Resilient Kids While Staying Cool, Calm and Connected.
If you're one of the lucky parents whose child is "More Intense, Sensitive, Perceptive, Persistent, and Energetic," you'll find wonderful advice in Raising Your Spirited Child, by Mary Kurcinka.
I wish you all well.