Smiths wield guns and roses

Brad Pitt and Angelina Jolie play a married couple and assassins who have each other in their sights.

Brad Pitt and Angelina Jolie's film Mr and Mrs Smith is all gun-wielding action. But the A-list actors and director Doug Liman say the movie is really a romantic comedy.

"The movie to me plays so much more on the level of relationships," Pitt said in Los Angeles this week. "This thing could have so easily devolved into an action thing.

"Any action that did take place was secondary, surrounding whatever argument they [Mr and Mrs Smith] were having at the time or whatever personal dynamic they needed to work out."

Mr and Mrs Smith tells the story of a happily married couple, Jane and John Smith (Jolie and Pitt), who have seemingly normal lives with normal jobs.

However, they are both secret assassins - but neither knows about their partner's real profession. The relationship is tested when the couple are commissioned to assassinate each other.

"I always viewed this that Brad and Angie thought they were in a romantic comedy," Liman, who is best known for directing films such as The Bourne Identity, Go and Swingers, said.

"They didn't think they were in an action movie because when you are having relationship issues, that stuff can sort of eclipse everything else. The outer context was a spy movie but they were in a love story."

That said, Pitt thoroughly enjoyed the opportunity to get physical in the film.

"I felt good, very good," Pitt said about the fight scenes with Jolie.

"I took some really good shots. Knowing the thing was not to be taken literally, we could go as far as we wanted to go, and to me it is one of the best comedic things of the thing."

Pitt had some fun when asked how to maintain "spice" in a marriage. "I think you are asking the wrong people," he laughed, possibly referring to his recent divorce and the twice-divorced Jolie.

In the film, Mrs Smith pretends to be the perfect wife - cooking, cleaning and keeping house. But in reality, she can't do any of those. Unbeknown to Mr Smith, she buys take-away and has never cooked in her life.

"We have all lessened ourselves in a relationship or a situation to blend in or make people feel comfortable but I don't think it is a good thing to do," Jolie said. "I think we should all be absolutely everything that we can be."

Australian Oscar winner Nicole Kidman was originally going to star in the film opposite Pitt but had to pull out because of commitments on The Stepford Wives.

"There was a lot of interest in the film but from our side, the only person we ever had a conversation with after Nicole was Angie [Jolie]," Liman said.

"There are not many Hollywood action movies with female roles which are this strong, so she had to be his equal - if not slightly better."

There has been intense scrutiny about the nature of Pitt and Jolie's relationship during shooting of the film and in the lead-up to the film's release.

That was heightened by the break-up of Pitt's marriage to fellow actor Jennifer Aniston and tabloid magazine articles suggesting the Hollywood heart-throb had embarked on a new relationship with Jolie.

Journalists interviewing the actors about the film were asked to sign legal documents, saying they would not ask about the stars' private lives or write anything disparaging. "I think freedom of speech is important but I also think we can be very sloppy with it," Jolie said when asked about freedom of speech.

"Sometimes there is so much that we actually don't even really hear each other and hear the important things and it becomes just excitable news.

"And the idea of what freedom of speech is, is misused in terms of something that is shonky and shallow and not what it was really meant to be."

More than 30 paparazzi photographers waited outside the Santa Monica hotel where Pitt and Jolie did press for the film in the hope of snapping the actors together.

"I believe freedom of speech to be everything, that everyone should have," Pitt said when also asked about freedom of speech.

Neither cast nor directors were keen to commit on a sequel to Mr and Mrs Smith, but suggested children might change the dynamics of the couple's relationship.

"It always comes down to script and if the script worked it is a possibility - but who could say at this point?" Pitt said.

Jolie said it was too early to commit to a sequel but suggested it would be interesting to see how having children might fit in.

"If you were to take it to the next evolution it would be that they could take on pretty much anything but I bet you a bunch of little kids would take them on and there is something beautiful about that," she said.

"No matter how tough they are, that would be their greatest challenge."

* Mr and Mrs Smith is in cinemas now

- AAP