"If they had governed well when in power, there would have been no need for protest walks," Sirisena said while addressing a religious gathering in the central town of Mawanella.
"Why walk on the roads until you get blisters on your feet?" he mocked.
Sirisena added that the former president's "greed for political power" was the reason behind the opposition's protest walk.
Rajapaksa said they were protesting Sirisena's "repression" and action which have left economic burdens on people. He said his group was also opposed to Sirisena's plan to sign the Economic and Technical Cooperation Agreement (ETCA) with India.