Silence the `unknown suffix -- ignored` error

In a directory with many subdirectories, I have some .gz archives. I want to recursively extract all these archives using gunzip. Hence, I use:

gunzip -r myDir

However, this command exits with "non-zero exit status 1" when there are some files in myDir that are not archives, with the errors being:

gunzip: myDir/dir1/file1.vcf.gz.tbi: unknown suffix -- ignored

Any idea how I can silence this particular error/warning?