Can police enter a private property?

They can enter private property under certain circumstances. These include sudden emergency, a warrant, invitation and hot pursuit.

Depends on why they are there. To snoop around without any probable cause, nope. To walk onto property and ask to speak to you, yes. You are free to say no and request they leave. To enter a home or outbuilding with a search warrant, yes. To enter a home or outbuilding with an arrest warrant, yes.

You won't find it in a local ordnance but instead in the Constitution. More precise, case law interpretation of the Constitution and more specifically, the Fourth Amendment. Police cannot enter private property unless they have a warrant signed by a judge, consent or permission of the owner, or an emergency circumstance exists that negates the usual warrant requirements.

The 4th Amendment to the US Constitution gives all of us the right to be secure in our persons, houses and effects from unreasonable searches or seizures by police without a warrant. So under normal circumstances the police cannot enter private property without a warrant. Remember the operative word in the 4th is "unreasonable" searches so there are exceptions to the warrant requirement.