Minor revision- Editor implied to do the experiment, however a rebut would clarify the issue
Answer: Contact the editor and ask if they would consider a rebuttal.

Reason: Had a very similar situation: one of three reviewers wanted an extra experiment and the editor indicated we needed to consider running another experiment. We contacted the editor and asked if they would be willing in principle to consider a rebuttal rather than running an extra experiment. They said that they would consider it but would give us no guarantees other than that. We were successful: the reviewer backed down.