Lucho Gonzalez scored the winner for the visitors at Vienna's Ernst-Happel-Stadion on Wednesday, leaving Bjelica frustrated by his side's lack of efficiency up front after they failed to convert one of their 13 shots, while Porto had nine efforts on goal.
Vienna had failed to win one of their three matches prior to their Champions League group stage debut and Bjelica expressed his pride but blamed their form on their struggles in the forward third.
"We can build on this performance," the 42-year-old Croatian said.
"I'm proud of what my team showed today.
"Of course, we lacked efficiency in our attacks but our tactical and physical approach to the game was something we can all be really proud of.
"In recent games we have squandered too many chances and that was the case again tonight. It's definitely an aspect we need to work on in training."
Vienna qualified for the group stage of this season's Champions League after overcoming Iceland's FH Hafnarfjardar and Croatia's Dinamo Zagreb in the qualifying rounds.
Wednesday's clash with Porto marked Vienna's first appearance in the group stages of Europe's leading continental competition, although the Austrian club did reach the quarter-finals three times during the European Cup era, while they also made the semi-finals in the 1978-79 season.
Bjelica claimed Vienna learned against Porto they can match 'the top European sides', although he emphasised the challenge for his team due to the difference between the two clubs' finances.
"Tonight my team represented themselves almost perfectly," Bjelica said.
"We made only one mistake at the back and we were punished. We will try to turn it around with hard work.
"That said, there's a difference of about €200million between the teams but you couldn't see it out on the pitch."
Porto's head coach Paulo Fonseca praised Vienna after the match, claiming the home side 'made our lives difficult'.
Fonseca was also pleased with Porto's 'pragmatic and calm performance' and said Vienna will trouble Group G rivals Atletico Madrid and Zenit St Petersburg.
The 40-year-old coach also hailed his captain Gonzalez for leading the visitors to victory.
"Atletico and Zenit will struggle here if Austria Vienna play like they did today," Fonseca said.
"However, Lucho is my commander, his experience can make the difference and he showed this again today."
