The contractile protein of skeletal muscle involving ATPase activity is -

The thick filaments of a myofibril are made of the protein myosin, and the thin filaments are made of actin along with tropomyosin and troponin.
Each myosin molecule (meromyosin) has a globular head with a short arm and a tail.
The globular head is an active ATPase enzyme; it has binding sites for ATP and active sites for actin.
It hydrolyses ATP, and the energy released is used to form cross bridges with actin and to pull the thin filaments towards the centre of the A band (sliding filament theory).
Actin has no ATPase activity in contraction.
Tropomyosin and troponin are regulatory proteins: they mask the active sites on actin in the resting state and uncover them when $Ca^{2+}$ binds to troponin.
So the contractile protein with ATPase activity is myosin.