Totti, who turned 38 on Saturday, chipped the ball over goalkeeper Joe Hart for his landmark goal which resulted in City failing to win their first home match in the competition for the fourth successive season.
City went ahead in the fourth minute when their former defender Maicon put his arm around Sergio Aguero and pulled him down leaving referee Bjorn Kuipers no alternative but to award the penalty which the Argentine swept home sending Roma's stand-in keeper Lukasz Skorupski the wrong way.
But City failed to build on that early advantage and although they played better in the second half when James Milner and Frank Lampard came on as substitutes, impressive Roma were worth their point.
Roma, who have won all five of their Serie A games since the start of the season and beat CSKA Moscow 5-1 at home in their opening Champions League match two weeks ago, played some crisp, sharp football after falling behind, and were unlucky not to be on level terms almost immediately.
A quick break ended with Maicon, who began the move marauding down the right flank, smashing his angled shot against the bar.
Gervinho almost scored from a similar position at the end of the first half, but Hart did well to save his powerful shot.
City, third in the Premier League, needed a result after losing their Group E opener 1-0 at Bayern Munich, but were largely second best in the first half.
They cancelled out Roma's creativity after the restart, but failed to find the breakthrough.
The draw left Bayern Munich, who won 1-0 in Moscow, top with six points, followed by Roma on four, City on one and CSKA bottom with no points.
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