Permission denied (publickey) : Github with Atom

I ran into a problem trying to clone github projects by atom. Using the terminal with you and another client git also only in Atom generates this difficulty:

linux-ssh: using SSH command [ssh]
Warning: Permanently added the RSA host key for IP address ‘…’ to the list of known hosts.
Permission denied (publickey).
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.

how can I solve ?

Are you able to clone projects outside of Atom?