The Wisconsin Congressman says he wants to focus on his work in Congress. Ryan is the new chair of the powerful House Ways and Means Committee.
It tackles major financial issues including taxes, social security and health care.
Ryan was the Republican nominee for vice president in 2012, and ever since, there has been speculation that he might seek the top spot, in 2016.
Wisconsin Gov. Scott Walker has said in recent months, that he would not run for president - if Ryan entered the race.