Will the dehumidifier make our rooms warmer in summer?

Yes, moderately. Depending on the type of dehumidifier i.e. compressor or desiccant it may increase the temperature in the room by a few degrees. The extent to which the room temperature may rise will also depend on the size of the room, the rooms’ initial temperature and the amount of time the dehumidifier is operating i.e. the longer it runs the more warm air it produces.
Note: Desiccant type dehumidifiers can produce more warm air than compressor types in warmer temperatures.