Not directly, the reason is that classic Nagios 3 or 4 uses a complete different approach for the service checks. Mostly active checks in Nagios compared to most checks passive in CMK.
What you can do is export a list with host names and IPs from your Nagios system and then make a mass import with this csv file in to CMK.
Now you can assign the proper configuration for every host (SNMP community if needed, agent type and so on).
In the end there are many manual steps and the only “migration” is the host list and IPs are the same 