Vettel's Aston Martin start was hampered by issues in pre-season testing, which restricted his mileage and opportunities to adjust to the AMR21.
The four-time world champion qualified 18th in Bahrain after encountering double yellow flags on his final Q1 hotlap but was demoted to last on the grid after stewards decided he hadn't respected the second yellow sector.
From 20th Vettel made a solid start but started struggling with tyre wear earlier than his midfield rivals.
He then received a 10 second penalty for running into the back of Alpine's Esteban Ocon, which put paid to his chances of scoring points on his Aston Martin debut as he came home in 15th.
When asked by Motorsport.com how frustrating his first race with Aston Martin had been, Vettel admitted he doesn't feel at home yet in his new car and said there are lots of issues his team needs to address.
"It's probably not the weekend we were looking for but there's a lot of things that we learned in the race that we need to address," Vettel replied.
"We will see how quickly we can fix them but I'm not at home in the car. There's a lot of things that are fighting me so that I can't really focus on driving. We need to address them and try and fix them."
Vettel explained the issues he's facing go far beyond him getting used to a different car, having moved to the Mercedes-powered team after five seasons at Ferrari.
When asked how far the team is from running at 100 percent, Vettel admitted it was "probably less than half" and he hoped solutions can be found quickly.
"I would probably say less than half as there's so many things going on still that break the rhythm and make it quite difficult in terms of feeling the car and feeling what I need to do to drive fast, so there's still a lot to do," the German explained.
"I obviously adapt to how the car wants to be driven but there's obviously a lot of things that add certain inconsistencies that don't help. I hope we can fix a lot of it very quickly."
Despite a compromised start Vettel said he felt good in his new environment and is optimistic Aston Martin can still have a strong 2021 season.
"Yeah very good, I feel really good. Obviously, I'm a bit sorry for such a bad weekend because I know how much preparation goes in before the start of the season." he added.
"On the other hand, it can only go up from here. As I said, we learned a lot of things so it's a lot of work ahead of us but it is what it is and we have to tackle it step-by-step.
"It's probably not the start of the season that we wanted but I think the next couple of races will be very good for us to calm things down."