Snatch at
Definition 1 of 2
Pro Tip 1/3Sudden Action
The phrase implies a quick, impulsive action without much thought or deliberation. 
He snatched at the bread, starving after the long journey.
Pro Tip 2/3Physical Reach
It often refers to a physical movement of stretching out an arm to grab something. 
During the basketball game, he snatched at the ball to intercept the pass.
Pro Tip 3/3Emotional Impulse
The phrase can convey a sense of desperation or urgency in the speaker's action. 
After being trapped for hours, she snatched at the rope lowered to her.