Washington (CNN) The father of a victim in last year's deadly mass shooting in Parkland, Florida, had an emotional message for President Donald Trump Thursday: "Stay out" of the discussion about how to prevent gun violence until "you're ready to actually be a serious participant in this conversation."

In the wake of the two mass shootings in El Paso, Texas, and Dayton, Ohio, that left 31 people dead earlier this month, Trump signaled support for strengthening background checks on firearm purchases, only to back away from those positions after consulting with National Rifle Association chief Wayne LaPierre and conservative allies.

In recent days, Trump has pointed to mental health as the primary response to preventing future massacres. He tweeted Thursday night that he had "a very good meeting on preventing mass shootings," without specifying any potential policy direction.

"Talks are ongoing w/ both Republicans & Democrats. We are likewise engaging with lawful gun owners, survivors, grieving family members, law enforcement, the NRA, mental health professionals, and school officials," he said. "I am hopeful Congress will engage with my Team to pass meaningful legislation that will make a real difference and, most importantly, Save Lives!"

Describing Trump on Thursday, Guttenberg said, "My daughter died in Parkland. I'll live with that every second of every day. And he lied to me and all the other victims that day and he's done it again since the other mass shootings, when he talks about doing the right thing for a brief second and then he says, 'but I spoke to the NRA,' and he walks away from it."

Then directly addressing the camera, Guttenberg said, "So Mr. President, let me tell you something. I don't care about you.

"This is not about love or hate. I don't care about you. I care about what you do. And I hate what you are doing. Because you are using the pain of the victims of gun violence to speak in a way that allows you to look like you're going to do something but only to play games with their emotions and not do it in the end. I don't care about you, Mr. President, but I hate what you do. It is time for you to stop talking on this topic until you are ready to give (Senate Majority Leader) Mitch McConnell the go-ahead to open up the Senate and actually take on legislation. Enough. Stay out of this. Keep your mouth just quiet unless you're ready to actually be a serious participant in this conversation. Just stop."