Iran advanced with seven points, three ahead of India, whose 0-0 stalemate against Afghanistan means it will face either Oman or Uzbekistan in the third-place playoff.
Mohammad Mahdi Mohebbi gave Iran the lead in the 37th minute with Mohammad Mohebbi doubling the advantage two minutes into the second half.
However, Shahrom Samiev pulled a goal back for Tajikistan in the 57th minute before Zoir Dzurboyev leveled the score in the 77th minute.