I know how to read the Quran in Arabic but being an ajami, I have doubt reading it when I fast. One of the reasons of the fast being broken is to lie upon Allah.

I'm afraid that if I read the Quran and mispronounce any word, that will be counted as a lie against Allah and my fast will be broken, which obviously I don't want to happen.

So I tend to read Quran after fasting. My intention is to read Quran correctly but because of my doubt I don't read it during fasting. Can you please guide me on this?

Reciting quran and having spelling mistakes doesn’t mean as if someone has ascribed false things to Allah (swt). Ascribing false things to Allah means a person says something from his own side while it has not mentioned in the Holy Quran doesn’t matter that was positive comment or negative.
Therefore don’t worry about that you may recite Quran( you are not doing any mistake intentionally)
Our Amal carries more value while we are fasting.