United manager Mourinho is keen to bolster his ranks further after already strengthening his squad with the additions of Victor Lindelof and Romelu Lukaku.
But the Portuguese manager poured cold water on the possibility of an attempt to prise United legend Ronaldo away from Real Madrid.
"I'm not going to waste my time thinking about players who are mission impossible," Mourinho told reporters after the win.
Earlier, England striker Marcus Rashford scored twice with Marouane Fellaini, Anthony Martial and Henrikh Mkhitaryan bagging United's other goals in a one-sided victory in front of 25,667 fans at the StubHub Center.
Lukaku missed one golden chance four minutes into his United debut, with his shot saved by Galaxy goalkeeper Brian Rowe.
However Mourinho was satisfied with Lukaku's "unselfish" display in leading the line.
"Lukaku is a target man, he plays with his back to opponents," Mourinho said. "A good thing today for me is to see that he's a team player. He's not selfish. He's not obsessed with goals.
"He was not that worried about himself, he was worried about the improvement of the team."
The teenager opened the scoring after only two minutes, punishing an error from Ariel Lassiter near the Galaxy penalty area to dart in on goal and place his finish beyond goalkeeper Jon Kempin.
The 19-year-old doubled his tally in the 20th minute, latching onto a clever pass from Juan Mata to make it 2-0.
- Rashford 'still growing' -
============================
Mourinho later revealed that Rashford, who looks to have added a physical dimension to his game, was still growing.
"It's just the natural evolution of a kid," Mourinho said. "He's already taller than when I arrived 13 months ago. He's three centimeters taller. He's put on some muscle but without any kind of specific work because his speed is his most important quality and we don't want to lose that."
Mourinho changed his entire line-up at half-time, mirroring wholesale changes made by the Galaxy.
United got their fourth of the night on 67 minutes when Martial burst forward and threaded a pass to Mkhitaryan who made no mistake with a confident low strike.
Martial made it 5-0 five minutes later, rifling home Timothy Fosu-Mensah's pullback.
Galaxy meanwhile, who had failed to register a single attempt on goal in the first half, bagged two late consolation goals through Mexico international Giovani Dos Santos.
"That's what we need," he said. "They gave us two different teams they gave people with intensity, so it was good for us."
Mourinho was also satisfied with an experimental formation which saw him play with a three-man central defence.
"We tried a system that is not our main system," he said. "We were working a few days on this to try to make the players feel a new experience in a new position and I'm really happy happy with that.
"It's something we have to keep working and keep improving in case during the season we decided to play with three at the back. Maybe we want to do it more times."
Disclaimer: No Business Standard Journalist was involved in creation of this content
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
