The widespreed and common cipher in Perso-Arabic alphabet (first used by Arabs) is Abjad system which itself roots back to Phoenician alphabet.
The system consists of 28 letters. Each of them has a number assigned. The system isn't in the alphabetical order of Arabic language wchich also has 28 letters.
The Abjad order is as follows (right to left):
ا، ب، ج، د، ه، و، ز، ح، ط، ی، ک، ل، م، ن، س، ع، ف، ص، ق، ر، ش، ت، ث، خ، ذ، ض، ظ، غ
The numbers are as follows (from left to right (the first number for ا)):
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000.
Since the Persian alphabet has four additional letters (پ، چ، ژ، گ), Iranians have added them after the last Abjad letter (غ) in the following order, again from right to left: گ، چ، پ، ژ
And the corresponding numbers are 2000, 3000, 4000, and 5000 respectively.
In the question we have the numbers: ۶۶۰ = 660, ۶ = 6, ۲۰۱ = 201, and ۲۳۳ = 233.
660 = 20 + 300 + 40 + 300 (four letters): کشمش (ک ش م ش)
6 = 5 + 1 (two letters): ها (ه ا)
201 = 200 + 1 (two letters): را (ر ا)
233 = 2 + 200 + 10 + 7 + 10 + 4 (six letters): بریزید (ب ر ی ز ی د)
کشمش ها را بریزید
It literally means "pour the currants"
کشمش (currant), ها (plurality sign), را (objective sign), بریزید (to pour in ordering form)
The commander has in fact ordered his troops to attack the enemy with mortars. Because "currant" is used in Iranian war vocabulary as mortar to avoid spyings.