zaustavljati

1. (+ acc.) to stop; to halt
   Policija zaustavlja svaki auto na granici. — The police stop every car at the border.
   Nemoj da me zaustavljaš, žurim na posao. — Don't stop me, I'm in a hurry to get to work.
2. (zaustavljati se) to stop; to come to a halt
   Ovaj autobus se ne zaustavlja kod pijace. — This bus doesn't stop by the market.
   Uvek se zaustavljamo na pumpi kod Niša. — We always stop at the petrol station near Niš.
3. (of a process) to hold back; to check
   Ovaj lek zaustavlja širenje infekcije. — This medicine stops the infection from spreading.

The perfective is zaustaviti; the meaning "to come to a stop" requires se.