Yes, a U.S. "administration" is the closest analogy to a "government" in the sense usually used in reference to parliamentary systems when talking about a particular leader's government or a change of government, as opposed to the government of the country ("Europe" is sort of beside the point here, as its more about form of government than geographic location.)
The agencies in the executive branch are 99% civil service people, not political appointees, and they don't change over every four years. The administration is the President, the cabinet, and political appointees, so I think that's the equivalent term.
I think that's correct in an academic sense. But in the day-to-day usage, I think Obama's “this administration” lined up pretty well with Cameron's “this government”.
The thing that changes in a change of "government" isn't the whole executive branch -- most parliamentary systems have a well-developed permanent civil service. What changes are the PM, cabinet, and some subordinate political rather than civil service officers. That's pretty much a precise parallel to a U.S. "administration", not the whole of the executive branch.