Chasing a target of 175, Bangladesh were all out for 144 despite being 110/2 in the 13th over.
"I think we had a chance looking at the way (Mohammad) Naim and (Mohammad) Mithun built a partnership. But we lost wickets rapidly and that cost us the game," he said.
Naim smashed 81 off 48 balls and put Bangladesh on cruise mode, sharing a 98-run stand with Mithun (27) for the third wicket. But Bangladesh lost their way after Mithun was dismissed by Deepak Chahar in the 13th over. Chahar had earlier got two wickets and went on take a hat-trick to finish with figures of 6/7 the best ever in T20 internationals.
Mahmudullah, however, praised the efforts of the team, which missed two of their biggest stars in all-rounder Shakib Al Hasan and opener Tamim Iqbal. The series was tied 1-1 and Bangladesh would have recorded a first ever series win over India in the shortest format of the game had they pulled off a win.
"We needed 49 runs in 5 overs... We had a chance, but we missed it. It was good to see the efforts the boys put in. We could not finish well after winning the first game," he said.
Twenty-year-old Mohammad Naim, who made his debut in the series, ended up being the top scorer of the series with 143 runs in the three matches.
"I think he (Naim) is a very talented batsman. The way he built his innings was very calm and composed. Also, all the three seamers executed their plans and bowled really well in the series," said Mahmudullah.
( With inputs from IANS )