@giranp Good morning. First of all: You're in the wrong forum. The port for ESP8266 is supported at forum.micropython.org.
Besides that, what you did is right. The information missing is:
a) which kind of board are you using?
b) did you set the access rights for /dev/ttyUSB0, or better, are you as user in the dialout group? You shoud get an error message if not.
c) When connected, try Ctrl-C or Ctrl-B or Ctrl-D, whether this changes the behviour.