Is it because of gravity that meteriods fall to earth?

Only partially. Meteoroids passing near Earth are affected by Earth's gravity, but they are traveling far faster than escape velocity, that gravity is usually insufficient to cause an impact. Rather, meteoroids strike Earth and its atmosphere when their trajectories around the sun intersect that of Earth such that they will pass through the same place at the same time. In the case of a near-miss, Earth's gravity will alter an asteroid's or meteoroid's orbit. In some cases this change can lead to a collision later on.