The judge also gave the soul diva a conditional discharge, meaning she will avoid further punishment if she stays out of trouble for two years.
"(That) may be harder than a fine, because you have now got to stay on the straight and narrow for the next two years," District Judge Peter Crabtree told Winehouse, whose scrapes with the law have often overshadowed her Grammy-winning music.
A scrum of photographers met Winehouse as she arrived at Milton Keynes Magistrates Court, 50 miles (80 kilometers) north of London.
The 26-year-old singer admitted charges of disorder and common assault during a Dec. 19 performance of the pantomime "Cinderella," starring Mickey Rooney. The petite singer had earlier admitted drinking five vodka and cola drinks that night.
Audiences at British pantomimes, or variety shows, are traditionally rambunctious and are encouraged to shout at the stage and join in with the songs. But prosecutors said Winehouse's behavior went beyond the usual audience participation.
Prosecution lawyer Julian Vickery said Winehouse had been "raising her voice in the spirit of the pantomime" during the show at Milton Keynes Theater. She "accepted in interview that some members of the audience may have found her disorderly," and one had asked her to be quiet, he said.
The attorney said Winehouse later left the auditorium to go the toilet and, passing the bar, asked manager Richard Pound for another drink. Vickery said Winehouse felt "hurt, embarrassed and patronized" when Pound suggested she have a glass of water instead and then asked her to leave.
He said Winehouse "with no premeditation, grabbed his hair and pulled."
Winehouse, dressed in a white shirt and dark skirt with her beehive hair piled high, admitted Wednesday that she had lashed out at Pound.
The judge said it was "obvious that alcohol played its part" in the incident. He said a medical report showed the singer had since tried to curb her drinking.
"You clearly have taken effort from this report to address your alcohol problems and any other problems you may have, so you get credit for that," the judge said.
Winehouse had been charged under her married name, Amy Civil, after reporting to a police station Dec. 23.
The singer shot to stardom with the Grammy-winning album "Back to Black" in 2006, but her music has been overshadowed by drug use, legal run-ins and a tempestuous marriage that ended in divorce last year.
Winehouse was acquitted last year of assaulting a fan who asked to take her picture after a charity ball. The judge said he could not be sure the blow had been deliberate.