The much-anticipated bout looked unlikely after Mayweather was sentenced to 90 days in prison for assaulting his ex-girlfriend, but the WBC welterweight champion has recently had his jail term delayed.
The 34-year-old said on Twitter: "Manny Pacquiao I'm calling you out let's fight May 5 and give the world what they want to see.
"My Jail Sentence was pushed back because the date was locked in. Step up Punk."
The unbeaten Maywether's most recent fight came last September when he defeated fellow American Victor Ortiz by knockout.