Translation:Don't be nervous! I will help you.
Except that 紧张 literally means "nervous," not "worry." If they wanted to say "Don't worry," the Chinese would be 别担心。 I agree it sounds strange in English, as "don't be nervous" is not something we'd normally say in this context. But the literal translation is not the same as the original sentence.
Can any native Chinese speakers confirm this, please? I'm quite certain of the meanings, but it's always good to have native-speaker confirmation.