“Both of them are professional enough to handle the situation,” the German told reporters ahead of the fourth race of the season.
Rosberg and double world champion Hamilton went wheel-to-wheel at Sakhir last season and this year’s race has been spiced up by a spat between the team mates in China last Sunday.
Rosberg accused Hamilton, who won in Shanghai from pole position, of compromising his race by not driving quick enough while leading and exposing him to the threat of Vettel immediately behind.
Hamilton suggested Rosberg had not tried hard enough.
A clash between the two on Sunday would likely benefit Vettel, the winner in Malaysia who has finished on the podium in his three races with Ferrari since leaving Red Bull, but he is not counting on it.
“For us, it is irrelevant,” he said. “We need to look after ourselves, and if they are in trouble with each other and take each other out, everyone benefits, not just us, so it would be welcome.
“But equally we are not expecting that. As I’ve said, they are professionals and they know what they are doing.”
Vettel famously collided with his Australian team mate Mark Webber at Red Bull in 2010, while Rosberg and Hamilton made contact in Belgium last year with the Briton retiring from the race.
They also went wheel to wheel in Bahrain in what turned out to be one of the thrilling races in a season dominated by Mercedes.
Hamilton is again leading the championship, 13 points clear of Vettel and 17 ahead of Rosberg, but Ferrari are far more competitive and ready to pounce.
“You have to be realistic,” said Vettel, who finished third in China. “Mercedes have the strongest package at the moment, both drivers are doing a very good job, which makes them difficult to beat.
“Hopefully, we can be a little closer here compared to last week.
“I expect to be in a good position. So far this year, no matter the conditions, the ambient temperature, track temperature, I’ve always felt comfortable in the car,” added the German.
“It seems to work in all sorts of conditions — dry or wet, hot or cold — so we should be in reasonable shape.”
(Editing by Ed Osmond)