Nagel said that he never received direct communication from the ministry, but was told after trying to donate in December, that he could be arrested if he did not stop.
He has flown to Israel three times in the past year to donate.
"The Ministry of Health is saying, well how can you be a father to all these children, well you know, I'm not a father to all these children," Nagel said.
"Obviously I can't be a full-time dad to all of them."
Nagel says he often meets some of his biological children and their parents for group playdates, and emphasises how important it is that they know their biological siblings.
His Jewish Orthodox family is ashamed of what he does, according to Nagel, and would prefer that he "settle down and have a traditional marriage".
But Nagel says its "impossible" to be in a relationship while trying to help other women conceive, and he doesn't plan to stop any time soon.
"My heart does tell me to continue. I know and feel that I'm doing the right thing. If what I was doing was wrong, it wouldn't feel so right," Nagel said.
-AP