There aren't really any quotes in "The Second Coming" in which Yeats directly says he wants to prevent change. However, the poem seems to fear coming change in general and so, while it would be difficult to say that Yeats definitely wants to prevent change, one could say that the entirety of the poem is apprehensive of change.
"The Second Coming" was written during a time of great turmoil. The first World War had just ended, and Yeats' native Ireland was in the midst of a gritty war for independence from Great Britain. As such, it's easy to understand why Yeats' general outlook was gloomy and why the poet chose to write a poem as pessimistic as "The Second Coming." Indeed, the poem's most famous line ("Things fall apart; the centre cannot hold" ) seems to predict an apocalyptic downfall and the collapse of society. As such, though one cannot say that Yeats is directly trying to prevent change, one could say that "The Second Coming" is a depiction of a tumultuous time and a representation of a narrative voice that fears for the future that societal changes will bring.