During the time that John F. Kennedy was in office, the Civil Rights Movement grew in strength. It did so mainly on its own and not really because of anything that Kennedy or his administration did.
During most of his presidency, Kennedy needed political support from Southern Democrats. For this reason, he was reluctant to come out strongly in support of civil rights. With Kennedy relatively quiet on the issue, activists were the ones who had to drive the movement forward. It was during these years that the nation saw the Freedom Riders and the marches for voting rights in the South. It was during Kennedy's time that Martin Luther King led the March on Washington. In other words, the Civil Rights Movement grew a great deal during that time.
The Civil Rights Movement became much more powerful during Kennedy's time in office but most of that growth was fueled by the activists themselves, not by Kennedy's policies.