Mead, who claimed the Golden Boot and player of the tournament award when the Lionesses won the Euros last summer, misses out after sustaining an anterior cruciate ligament injury in November.
Asked if there was ever a chance the Arsenal winger could have been in the squad, Wiegman told a press conference: “No, I don’t think so.
“Beth is so positive and she’s going really well, but we said the time schedule she had, we would have taken so many risks to try to get her to the World Cup.
“Very early we said we’re not going to take that risk, I’m not willing to take that risk, to push her too much and then she gets injured again. We have to take care of players and do what’s smart, and not do what’s a little bit naive.”
There is a recall for in-form Bethany England, back involved for the first time since last September.
The forward has scored 12 Women’s Super League goals for Tottenham after joining from Chelsea in January, and Wiegman said: “She was at Chelsea, she didn’t get the minutes.
“Then she made a move and started playing. Tottenham was having a hard time, but how she performed and how much resilience she showed – I think that’s what made us make the decision to get her in the squad.”
Wiegman confirmed Bright is set to captain the side, and regarding her and Bronze’s recoveries from knee surgery, she said: “Lucy is fit and fully in training, and Millie is in a good place, so we’re positive.
“She’s still building but we have some time. We need to build a little more but it looks good.”
On Williamson’s absence after suffering an ACL injury of her own in April, Wiegman said: “Of course, most of all for her it’s very disappointing and sad, and that’s the same for Fran and for Beth Mead.
“But you have to move on too. This is unfortunately part of top sports, that you can get injured. You hope to make that risk as small as possible but it can happen and someone else steps up and it gives an opportunity.”
Jordan Nobbs is included despite sustaining an injury in Aston Villa’s penultimate game of the season, Katie Zelem has been brought back after not making the last squad in April, and there is no recall for Williamson’s predecessor as captain Steph Houghton.
Jess Park, Maya Le Tissier – who Wiegman said was “really close” to making the 23 – and Emily Ramsey have been named on standby.
Wiegman said there had been “hard decisions” and that while some players were missing through injury, she still feels “we have a very good squad, very good depth in the squad.”
England get their campaign at the tournament in Australia and New Zealand under way by facing Haiti in Brisbane on July 22, and will also take on Denmark and China in Group D.
Wiegman was also asked about the diversity of the squad in terms of there being 21 white players out of 23, and said: “Of course I understand that people look at it like that, and I really hope that will change, but that won’t change overnight.
“I know the FA is doing lots of things, with ‘Discover My Talent’, ‘Let Girls Play’, to get everyone who wants to play football, whatever background you have, or wherever you come from, that you have access to it.
“I think what our players did after the Euros, (asking to) have access in schools, which now had a big result, hopefully that brings more girls with different backgrounds into the game, so in the future we have more players from different backgrounds in the national team too. But for now I think that takes a little more time.”