You can either build a rules engine from the bottom or use any of the Python parse libraries to get you started. The second option can save you a lot of time. Take a loop at these libraries:

https://pypi.python.org/pypi/parse

https://pyparsing.wikispaces.com/

These will help a lot in interpreting your sentences. From there on you could define your generic conditions and actions in classes. The feasibility for this depends a lot of the complexity of the actions you intend to do.

If you need more complexity than just a few basic instruction you might want to take a look into themes like "building a DSL (domain specific language) in Python" or in slang "mini-languages". Check for instance this presentation in slideshare:

http://www.slideshare.net/Siddhi/creating-domain-specific-languages-in-python

Hope it helps.

Dear Mr Latifi, I suggest you to take a look on Pyke (http://pyke.sourceforge.net/) or Intellect (https://pypi.python.org/pypi/Intellect)

Best regards.

As Reisel González Pérez  has mentioned, Pyke is the packages which give you the ability of developing rule based systems.

Besides the given links above you can see some Pyke examples here : http://cyberdelia.github.io/pricing/ 

Thanks Pedro for your good helping note, actually I´ve used Stanford parser to analyze sentences. I´ve already  defined class to add condition and action. My question is about to run action when all of the conditions are satisfied. My goal is reducing the running time while some conditions are not true. Are there commands to run all action in rule base?

Thank you very much