akka-actor: java.lang.OutOfMemoryError: unable to create new native thread

Question

I have an actor which is causing:

java.lang.OutOfMemoryError: unable to create new native thread
    at java.lang.Thread.start0(Native Method)
    at java.lang.Thread.start(Thread.java:719)

Actor is created like this:

context.actorOf(MyActor.props)

Actor itself doesn't create any child actors. It basically tries to make a network call and do further processing.

Any lead where to look for cause? Can it be code in the actor itself?