That base flag does not mean anything. Iran's three-color flag was chosen by Qajar dynasty. Pahlavis did not change the flag in their reign either, it is this one:
but Islamists, mullahs, tried to change the flag. Due to the mullah constitution, the flag should have the word Allah Akbar, but Khomeini wanted the coat of arm, which is like sikh religion coat of arm, be placed in the flag, aka this one:
So, they finally decided to put this sikh type coat of arm in the middle of flag as Khomeini wanted it, and wrote Allah Akbar in the edges of the flag, so it became this one:
But, most Iranians do not recognize this mullah invention as their own flag, and prefer the Qajar-Pahlavi flag.