If someone were to speak to me like that, I'd call the police.
Literal
By-chance someone [subject-が] in-that-way me [to-に] speak-came-[conditional-なら], I [topic-は] police-officer [object-を] will-call [probably-だろう].
Uses the conditional なら after past-tense きた (きたなら) — a slightly literary variant. そのように ('in that way, like that') is the manner adverb from そのよう. 話しかけてくる ('come and speak to [me]') combines 話しかける ('speak to') with the directional ~てくる.