AFP-- "The people of Yemen will make their aggressors regret their actions," Rouhani said in a televised speech.
His comments came a day after the killing of ex-president Ali Abdullah Saleh and a renewed Saudi-backed offensive on the Yemeni capital Sanaa.
Saudi Arabia has been leading a coalition against the popular Huthi forces in a war that has cost thousands of lives and become the world's worst humanitarian crisis according to the United Nations.