Your first step may be to report the officer to his/her internal affairs department. This is a unit of the police department that is dedicated to addressing abuses by police officers. Not all police departments have an IA Desk and not all IA are diligent in their case work. So if you are not able to use this route or are unsatisfied with the resulted you have other options.
Some other options you have is to report the incident to the FBI. The FBI is responsible for investigating criminal abuse of power(color of law) allegations, such as the type mentioned in the question. Chances are your case will not go anywhere unless there has been a pattern from the officer. But your case could help provide evidence of the pattern in the future against the officer. Part of the problem is going to be proving that the officer did not have probable cause and no exigent circumstances existed that prompted the search. "I thought I heard someone yell for help", or I smelled smoke and thought that evidence may have been in the process of being destroyed are 2 common exigent circumstances that are difficult to disprove. But an officer that consistently uses these nebulous excuses may provide the type of pattern needed for the FBI to take action.
In the US you could take the case before a grand jury and pursue an indictment against the officers there. The reality is that getting in front of the Grand Jury to present a case is very difficult unless you are a lawyer, preferably a states attorney. But if you can get in front of the jury and present evidence that the law has been broken, the grand jury can usually be convinced to indict. The bar here is much lower than it is to convict at trial.
You could also pursue the case in Civil court. For this you will want a lawyer and the cost will usually be high unless you have the type of evidence that a Lawyer might be willing to take the case on contingency. The Civil court will require that you be able to show damages from the act, but has a lower bar for a finding in your favor than does a criminal court.