Remove the leaves by hand. This method will work especially well when when few leaves are in the gravel and they're bigger and dry. Wear garden gloves to keep your hands clean. In areas where neighbors are sensitive to loud noises, such as from leaf blowers, removing leaves by hand is a good choice.
Rake the gravel and leaves. Use a rake with round wire tines that are more flexible than stiff, so that you'll move more leaves than gravel. Avoiding rakes that have sharper ends will help prevent spearing the leaves, which will make removal easier.
Blow the leaves. If the leaves aren't wet or embedded in corners, using a leaf blower can be effective. A leaf blower, for the most part, will blow the leaves and not the gravel, making the process easier if your gravel bed borders a grass lawn.
Vacuum the leaves. Home and garden stores in your area may sell garden vacuums. These are designed to suck up lighter debris, such as leaves and grass, while leaving soil and gravel on the ground. Some models may even pick up wet leaves fairly easily.
Torch the leaves and gravel. Devices called "flamers" burn propane or butane to form a sustained flame that's designed to destroy weeds. It will just as effectively destroy leaves in gravel, thereby "getting them out." Don't use this method during severely dry conditions or when the gravel is surrounded by dry, combustible material.