The phrase "unnecessary pressure" means that a certain amount of stress or expectations are being placed on someone or something, but it is considered excessive or not required. Full definition
Because the buttons are on the top of the earbuds, they don't put unnecessary pressure on the inner ear like others do with a button that pushes inward. (tomsguide.com)
Your elbows should be directly under your shoulders to ensure proper weight distribution, while the spine should remain straight all the time to avoid putting unnecessary pressure on the neck and back. (fitnessandpower.com)
You don't need to put yourself under unnecessary pressure. (myfinancekits.com)