Mayor Bill de Blasio on Thursday defended as “absolutely appropriate, absolutely ­legal” his trip to Israel this weekend funded by a Jewish businessman.

The $20,000 to $25,000, three-day trip includes his and four aides’ expenses.

The lefty Center for Constitutional Rights said the funding by Brooklyn-based Israeli entrepreneur Baruch Eliezer Gross “marginalizes the perspectives of those who suffer from Israeli policies.”

Noting Gross does no city business, the Conflicts of Interest Board OK’d the trip , authorities said.

The mayor called it “very important” to stand with Israel.