Are you accessing Binance Services from a restricted region? Some products may not be accessible in certain countries, I suggest having a look at the terms of use to confirm this is not the case.
I guess only GET requests are allowed , I just tried GET /api/v3/account (HMAC SHA256)
It worked as well.
Anyway , Let me check Binance.us APIs.
Update → Using Binance.us did not work as my account is in Binance.com , so API keys would be different. I’ll try to trigger POST requests from a different region other than US , but that’s weird that GET is allowed but not POST , ideally it shouldn’t be allowed if at all.