Levi on Bristol & Tripp's PSA: "Sending Out a Good Message"

Bristol Palin's new PSA for May's National Teen Pregnancy Prevention Month that features her son Tripp has his dad, Levi Johnston, speaking out.

OK! VIDEO: BRISTOL PALIN PREACHES PREGNANCY PREVENTION IN NEW PSA

"Every time I tried to put him on TV she'd flip out — but it is nice to see him on there; he's happy and he's looking good," Levi told Entertainment Tonight in an interview that airs tonight. "Bristol is sending out a good message."

"Telling people how tough it is — I know when I have him it is tough," Levi said of the PSA message. "It's not about you at all; you've got to watch him constantly. But it's amazing, too. I wouldn't go back and change it for anything. I love it."

"It's the best thing that's ever happened to me, so I'm sure Bristol's thinking the same thing," he added.

OK! NEWS: BRISTOL PALIN TO PLAY HERSELF ON SECRET LIFE OF AN AMERICAN TEENAGER

Levi and Bristol's relationship has been improving, but he's still trying for joint custody.

"She and I talk quite a bit more now. I get Tripp at least once a week now, and things are definitely 100 percent better than they were," he said. "I'm just kind of playing by her rules until I have him."

OK! NEWS: BRISTOL PALIN TELLS LEVI JOHNSTON TO GET A JOB

"I'm going for joint custody; I'd never go full custody," he explained. "I wouldn't try and do what she's doing to me. I wouldn't want to do that to a mother. It's just not right, anyway."