This guide shows how to import into pass your passwords stored in Apple's Keychain Access.
The default kaychain file is ~/Library/Keychains/login.keychain.
Passwords under the "Local Items" keychain (the default since Mavericks to sync with iCloud) use a different file format and can not be exported via the Apple's security tool we use. If that is you case, create a new keychain and drag-and-drop the keys. Your new keychain should have the .keychain extension.