"We have not asked and will not ask for permission to develop different types of ... missiles and will continue our path and our military power," Rouhani said in a speech at Tehran's Azadi (Freedom) square, where tens of thousands gathered to mark the 40th anniversary of Iran's Islamic revolution.
Rouhani also vowed Iran would defeat US sanctions, reimposed after President Donald Trump withdrew from Tehran's nuclear accord with world powers last year.
"The Iranian people have and will have some economic difficulties (due to the sanctions) but we will overcome the problems by helping each other," Rouhani said.