Coinbase denies transaction: Please complete verifications to send money
I finally got assistance from the support agent David. He has explained the situation in details and helped me to solve the problem.

To pass verifications, I needed to confirm email &amp; phone on this page

https://www.coinbase.com/verifications

Then I uploaded my ID photo on this page:

https://www.coinbase.com/verifications/documents/new

After that I have filled the following form with correct address &amp; credentials:

https://www.coinbase.com/settings/personal_details

After that I was finally able to send the BTC.

Thanks for patiance a assistance, David!