Google's new app recites answers to search results in a human sounding voice, similar to Apple's Siri, which some analysts and technology observers believe could make iPhone users less reliant on Google's search service.
The news comes as the relationship between the two companies grows increasingly competitive. On Monday Apple said it would no longer offer Google's YouTube app as a pre-loaded app in future versions of its iPhone.
Google, which unveiled a version of the voice-based search app for its Android software earlier this year, showcased the version for Apple devices at a press event at its San Francisco offices on Wednesday.
The company also announced a test version of a new service that will integrate users' personal emails into searches on the Google website. The service, which Google said will initially be available to 1 million users, aims to make it easier for consumers to access information such as flight schedules or shipping orders.
A truly universal search will "have all the information that humanity has put on the Web and information that's your information," Amit Singhal, senior vice president of Google Search.
The initial "field trial" will work with Google's Gmail, but Singhal said the company was open to working with other email providers.