Brooklyn Beckham and Nicola Peltz‘s absence from David Beckham‘s 50th birthday is all due to family tension … ’cause we’ve learned they tried to meet up and celebrate David privately — but, they were rebuffed.

Sources familiar with the situation tell TMZ … Brooklyn and Nicola flew to London last week — for the sole purpose of celebrating David.

The two reached out to the fam ahead of the big weekend, we’re told … asking them to get together privately before the birthday festivities — however, their request didn’t go over well with the other family members.

Our sources say Brooklyn and Nicola were told to show up to the main celebrations or they wouldn’t get a chance to see the fam … leaving the two saddened because they simply won’t be around Brooklyn’s brother Romeo and his girlfriend, Kim Turnbull.

We broke the story … Brooklyn and his brother Romeo aren’t on speaking terms because of his relationship with Turnbull — who Brooklyn had a romantic connection with several years ago, but that’s all water under the bridge now.

We’re told that even though they missed the party, they reached out to David privately to wish him a happy birthday … we’re told they’re not performative people — and, they prefer to discuss internal family matters privately.

As we told you … a whole bunch of celebrities showed up to support the former soccer standout and businessman for his golden bday — but, Brooklyn and Nicola were absent.

Victoria posted pics from the event and seemingly shaded her son … writing in the caption that they were “Creating special memories with family and friends” — without Brooklyn, that is.

While that’s ancient history now, sources previously told us Brooklyn doesn’t think Kim is in the relationship for the right reasons … so, Brooklyn and Nicola are avoiding all public family events.

Brooklyn and Nicola might not like Kim … but we’re told David and Victoria trust her — and, it’s clear they’re fine with her being around the family.