If you have an emergency and need assistance, and you are a US Citizen or resident, you may contact the US Embassy while there. Otherwise, please contact your corresponding embassy or consulate. If you need to call the police while there, you will want to dial 106 from a local telephone for any emergency. Otherwise, you can also dial 104 for an ambulance and 105 for the fire department. Note that you will not find an English-speaking person that answers.
U.S. Embassy contact information:
Calzada between L & M Streets, Vedado, Havana
Main switchboard (53) (7) 839-4100
Hours: 8:00 a.m. to 4:30 p.m. (closed on U.S. and Cuban Holidays)
Emergencies/After Hours: call main switchboard at (+53) (7)-831-4100, dial 1 to speak with emergency operator. If you get into trouble in Cuba (financial, medical etc.) and in in dire need, then we suggest you contact Asistur (Assistance to Tourists). Office locations, phone numbers, and fees for this company can be found here: http://www.asistur.cu/indexi.php
We suggest printing out a list of all emergency and hotel numbers and addresses to have in handy in case of an emergency