Yes, both sentences are correct but they emphasize different things: "The police officer who gave me directions was friendly." Focus: The key information is that the officer gave directions, and a secondary detail is that they were friendly. "The police officer who was friendly gave me directions." Focus: The key information is that the officer was friendly, and a secondary detail is that they gave directions. Summary: Both are grammatically correct; it just depends on what you want to emphasize.

Sentence #1: "The police officer, who gave me directions, was friendly." main clause: "The police officer was friendly." subordinate phrase describing the police officer: "who gave me directions" (Which police officer was it? The one who gave me directions) Sentence #2: "The police officer, who was friendly, gave me directions." main clause: "The police officer gave me directions" subordinate phrase identifying the police officer: "who was friendly". (Which police officer was it? The one who was friendly) In each case, the main clause is what matters most. The subordinate clauses give secondary information about the police officer. My conclusion is the opposite of the one reached in the previous comment. Commas to isolate the secondary phrase are helpful but not necessary.