Is there a csproj property which disables automatic NuGet restoration
for Visual Studio?
I'm afraid the answer is negative.
1.It seems you build the project within VS IDE. For nuget restore option, it's controlled by IDE level instead of .xxproj file level.
Go Tools=>Options=>Nuget Package Manager=>Package Restore
, you will find these two options :

Uncheck them, we can disable automatic NuGet restoration during build/rebuild, but we have to know it is an IDE option, not only for current project. If we create a new solution, this option is also disabled for the new sln.
2.Also, I understand why you want such property in .csproj. Usually,some settings in Project=>Properties
correspond to properties in .csproj.(Like build event,output path,target framework and so on).These options are for the specific project, so we can have corresponding property in .csproj. But nuget restore is for the whole IDE, which means there exists no corresponding property in .csproj.
3.In addition,the corresponding property is in nuget.config file(not in .xxproj).But it seems to work for entire solution in VS(not for per separate project). Just like the usage of Tools=>...Package Restore
. You may get some help from this issue.
Finally, you can consider build the project with msbuild command-line, it won't automatically restore nuget until you tell it to do so. Anyway,no default property in .csproj which disables nuget restore.
Hope it helps.