Immediately Shut Up Siri while on conference or phone Call manually

I have a Homepod in my office which I like very much. From my office, I make many conference and phone calls. On occasion, the Homepod will believe it hears a command (from the teleconference or phone conversation) and begins speaking a response. I want to know how to immediately stop Siri from speaking immediately manually so that it is not disturbing the conference or the phone call. Please help me understand how to do this.