NuGet.targets error installing packages.config using Xamarin Studio on a Mac

The Xamarin.Forms project was built in Visual Studio 2013. I am now trying to run the IOs app in Xamarin Studio on a MacBook. I've researched the web and the Forums, but I can't find any articles to assist me in fixing this problem. Here is part of error log.

Building Solution:

Target RestorePackages:
    Executing: mono --runtime=v4.0.30319 "/FILEPATH/.nuget/NuGet.exe" install "/FILEPATH/packages.config" -source ""   -RequireConsent -solutionDir "/FILEPATH/"
    /var/folders/4b/89kb4ktd5n71wsdvkkl7b4wh0000gn/T/tmp7a74846d.tmp: line 1: mono: command not found

/FILEPATH/.nuget/NuGet.targets: error : Command 'mono --runtime=v4.0.30319 "/FILEPATH/.nuget/NuGet.exe" install "/FILEPATH/packages.config" -source "" -RequireConsent -solutionDir "/FILEPATH/"' exited with code: 127.
Task "Exec" execution -- FAILED
Done building target "RestorePackages" in project "/FILEPATH/name.csproj".-- FAILED

Done building project "/FILEPATH/name.csproj".-- FAILED

Build FAILED.
Errors:

---------------------- Done ----------------------

Build: 1 errors, 0 warnings

There are 2 of these Build errors, but they are similar, so I'm only including one in this post.

Any help is much appreciated.

Thanks!