Cruz gave birth to baby Leo in January with her husband Javier Bardem.
Speaking to the Daily Mirror, Depp said "It's great to watch the three of them in action. It's just adorable and it makes you incredibly broody and clucky.
"They came to the house and I'd go to their place - to see new parents with their little angel definitely brings back memories. You start thinking, 'Oh wow, I'd like to have another one of those'. But I don't know... two's pretty good."
Depp also praised his long-term partner Vanessa Paradis, with whom he has a daughter, 11, and a son, 9.
"She's really amazing because she delivered those two beautiful children and she has the most difficult job out of both of us," said Depp.
"First of all she puts up with me, which I can imagine is not easy because I'm a little scattered now and again, but mostly she's inspiring. She's been a real leveller to me."
Watch the Pirates of the Caribbean: On Stranger Tides trailer below: