CSF can't block any massive attack, it's just can be used for small DDoS atacks 5-25 Mb/s.
Attack on my site more than 800 Mb/s so CSF can't help with this. Hardware firewall is too expensive and requires special settings and time to mitigate attack. So, I found best solution. It's CloudFlare firewall. As my site located in Russia, ddos bot's located in other countries like China, Turkey, India. I just checked a lot of bot's IPs and found more than 30 countries. CloudFlare free plan prevents block by country code, but again I found next solution, just create firewall rule with "CAPTCHA" check for every bot's country. As a result, most bot's denied to access my site. It's working very good now and this is free of charge.
So, thank you guys for your replies. Hope this can help anyone who have same questions and issues.