Greetings @Serghey,
First of all have you actually installed nmcli inside your container? Just because the binary is on the host OS does not mean it’s available inside the container environment.
Next in order to use nmcli from inside a container other than installation, some particular runtime arguments are required. Please see the answer on this post for specifics: Change the apalis imx6 static IP address from inside a container
Best Regards,
Jeremias