tabrez please ensure user name and pem file or password, is it existed on ami what you created.
first launch one machine and create a user and set password then install your required softwares if necessary.
then add the user in visudo, and enable password authentication in /etc/ssh/sshd_config file
restart the sshd service
finnally create an image and then use that ami in your migration, after migration try to login into the machine using previously created user and password.
sir created an ec2 instance using ami which i got after migration but cannot log into it even after giving the insecurefile path and user as vagrant