Yuvraj and Dhoni batted extremely well on a low, slow pitch as they took no risks during their 105-run stand for the fourth wicket to ensure a comfortable win.
Yuvraj hit one six and six fours in his 31st half-century, while Dhoni struck eight fours in his 17th.
Dhoni was caught behind off paceman Shoaib Akhtar with India requiring just 15 runs for victory with five wickets in hand.
"The start we got was excellent. Our bowlers bowled according to the field," said Dhoni, who was named man of the match.
|"The pitch was doing a bit and we knew if we got settled down we could go after the bowlers later."|
Mahendra Singh Dhoni,
"Murali Kartik and Harbhajan Singh have been doing well consistently and the conditions favoured the spinners.
"The pitch was doing a bit and we knew if we got settled down we could go after the bowlers later."
Pakistan won the toss and elected to bat before scoring 239 for 7 thanks to half centuries from middle-order batsman Mohammad Yousuf (83 not out) and left-handed opener Salman Butt (50).
Akhtar briefly raised Pakistan's hopes of defending the total when he troubled the Indian top order in a sharp four-over opening spell, but was unlucky not to get more than one wicket.
The fiery paceman had Sachin Tendulkar out for just four, trapped leg-before in his second over with a slower delivery that kept low.
Pakistan struggle in the field
Akhtar then came close to removing Gambhir early in the batsman's innings, with the ball going between wicket-keeper Kamran Akmal and first-slip Younis Khan and then eluding the outstretched right hand of the slip fielder for four.
The lapses proved costly as Gambhir (44) went on to add 82 for the second wicket with Sourav Ganguly (39).
"I think a target of 240 was defendable on this surface, but we dropped two-three catches," said Shoaib Malik, Pakistan captain.
"We were struggling a bit in the field. We learnt a lot from today's game.
"There are still four more matches to go and we hope to do better."
Harbhajan, Kartik and Tendulkar, Indian spinners, earlier played major roles in restricting Pakistan.
Part-timer Tendulkar took two crucial wickets, while off-spinner Harbhajan and left-arm spinner Kartik conceded just 65 from their combined 20 overs.
Tendulkar dismissed hard-hitting Shahid Afridi (31) and Malik (two) just when Pakistan threatened to cut loose.