Her remarks touched off a heated debate on social media.

“Really, Nikki?!” Michael Steele, the former chairman of the Republican National Committee, posted on Twitter, adding that Mr. Roof “inherited” the meaning of the Confederate flag.

Others online accused Ms. Haley of political posturing. In recent years, talk of a possible presidential run has circled Ms. Haley, who is considered a rising star in the Republican Party.

J.A. Moore, a Democratic South Carolina State representative, whose sister was killed in the church shooting, wrote on Twitter that Ms. Haley’s “continued use of this tragedy for political reasons is disgusting.”