"No worries" is a little like "no problem". Was there something I should have been worried about?
A possibility from English Language & Usage:
"It was no problem for me to hold the door for you, because your ease of access is more important than me getting to my car faster."
"The main difference is that you're welcome is meant to be polite while no problem is meant to be friendly."
I like this idea even though it's a bit hard to follow:
"Based on the other answers it seems not everyone has the following connotations with both terms, but I would argue that "No problem" implies that you did something out of the ordinary for someone, however that you did not consider it a problem. So in a sense you're disregarding the "thank you". In contrast "You're welcome" seems to imply that you appreciate their appreciation, as you in no way disregard their "Thank you".
Another idea from English Language & Usage:
In Italian from the site: Italian 101
Per favore is the most commonly used form of Please but there are other forms including
Grazie or Thank You, comes from Grazia meaning gratitude or consideration.
Grazie Mille, literally means a thousand thank yous or thanks a lot.
Other alternatives also include Non c’è problema, (No Problem!)
Di niente, (It's nothing)
From the link: Prego - a useful word | ITALY Magazine
Other languages have their own ways to say it.
Any ideas? "My pleasure" sounds best to me.