No – A good quality e-bike leaves you in control at all times – you choose how much assistance you want (if any) before you even start pedalling, and it only starts to help when you pedal, and even then sensors mean that assistance is only added in proportion to how firmly you push on the pedals. Assistance stops as soon as you stop pushing the pedals or apply the brakes, and you can alter how much it helps you pedal using the handlebar control whenever you want to, even on the move.
That said, it is however sensible to take some time away from busy areas to familiarise yourself with the assistance that e-bikes offer you, and look out for local groups like Pedalready who may offer courses to help you find out how to ride an e-bike to best effect.